[ Upstream commit e2e821095949cde46256034975a90f88626a2a73 ]
The function kdb_position_cursor() takes in a "prompt" parameter but
never uses it. This doesn't _really_ matter since all current callers
of the function pass the same value and it's a global variable, but
it's a bit ugly. Let's clean it up.
Found by code inspection. This patch is expected to functionally be a
no-op.
Fixes: 09b35989421d ("kdb: Use format-strings rather than '\0' injection in kdb_read()")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20240528071144.1.I0feb49839c6b6f4f2c4bf34764f5e95de3f55a66@changeid
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 70867efacf4370b6c7cdfc7a5b11300e9ef7de64 ]
When -Wformat-security is not disabled, using a string pointer
as a format causes a warning:
kernel/debug/kdb/kdb_io.c: In function 'kdb_read':
kernel/debug/kdb/kdb_io.c:365:36: error: format not a string literal and no format arguments [-Werror=format-security]
365 | kdb_printf(kdb_prompt_str);
| ^~~~~~~~~~~~~~
kernel/debug/kdb/kdb_io.c: In function 'kdb_getstr':
kernel/debug/kdb/kdb_io.c:456:20: error: format not a string literal and no format arguments [-Werror=format-security]
456 | kdb_printf(kdb_prompt_str);
| ^~~~~~~~~~~~~~
Use an explcit "%s" format instead.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 5d5314d679 ("kdb: core for kgdb back end (1 of 2)")
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20240528121154.3662553-1-arnd@kernel.org
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit c9b51ddb66b1d96e4d364c088da0f1dfb004c574 upstream.
Currently when the current line should be removed from the display
kdb_read() uses memset() to fill a temporary buffer with spaces.
The problem is not that this could be trivially implemented using a
format string rather than open coding it. The real problem is that
it is possible, on systems with a long kdb_prompt_str, to write past
the end of the tmpbuffer.
Happily, as mentioned above, this can be trivially implemented using a
format string. Make it so!
Cc: stable@vger.kernel.org
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20240424-kgdb_read_refactor-v3-5-f236dbe9828d@linaro.org
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 6244917f377bf64719551b58592a02a0336a7439 upstream.
The code that handles case 14 (down) and case 16 (up) has been copy and
pasted despite being byte-for-byte identical. Combine them.
Cc: stable@vger.kernel.org # Not a bug fix but it is needed for later bug fixes
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20240424-kgdb_read_refactor-v3-4-f236dbe9828d@linaro.org
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit db2f9c7dc29114f531df4a425d0867d01e1f1e28 upstream.
Currently, if the cursor position is not at the end of the command buffer
and the user uses the Tab-complete functions, then the console does not
leave the cursor in the correct position.
For example consider the following buffer with the cursor positioned
at the ^:
md kdb_pro 10
^
Pressing tab should result in:
md kdb_prompt_str 10
^
However this does not happen. Instead the cursor is placed at the end
(after then 10) and further cursor movement redraws incorrectly. The
same problem exists when we double-Tab but in a different part of the
code.
Fix this by sending a carriage return and then redisplaying the text to
the left of the cursor.
Cc: stable@vger.kernel.org
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20240424-kgdb_read_refactor-v3-3-f236dbe9828d@linaro.org
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 09b35989421dfd5573f0b4683c7700a7483c71f9 upstream.
Currently when kdb_read() needs to reposition the cursor it uses copy and
paste code that works by injecting an '\0' at the cursor position before
delivering a carriage-return and reprinting the line (which stops at the
'\0').
Tidy up the code by hoisting the copy and paste code into an appropriately
named function. Additionally let's replace the '\0' injection with a
proper field width parameter so that the string will be abridged during
formatting instead.
Cc: stable@vger.kernel.org # Not a bug fix but it is needed for later bug fixes
Tested-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20240424-kgdb_read_refactor-v3-2-f236dbe9828d@linaro.org
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit e9730744bf3af04cda23799029342aa3cddbc454 upstream.
Currently, when the user attempts symbol completion with the Tab key, kdb
will use strncpy() to insert the completed symbol into the command buffer.
Unfortunately it passes the size of the source buffer rather than the
destination to strncpy() with predictably horrible results. Most obviously
if the command buffer is already full but cp, the cursor position, is in
the middle of the buffer, then we will write past the end of the supplied
buffer.
Fix this by replacing the dubious strncpy() calls with memmove()/memcpy()
calls plus explicit boundary checks to make sure we have enough space
before we start moving characters around.
Reported-by: Justin Stitt <justinstitt@google.com>
Closes: https://lore.kernel.org/all/CAFhGd8qESuuifuHsNjFPR-Va3P80bxrw+LqvC8deA8GziUJLpw@mail.gmail.com/
Cc: stable@vger.kernel.org
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Justin Stitt <justinstitt@google.com>
Tested-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20240424-kgdb_read_refactor-v3-1-f236dbe9828d@linaro.org
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 4f41d30cd6dc865c3cbc1a852372321eba6d4e4c ]
When appending "[defcmd]" to 'kdb_prompt_str', the size of the string
already in the buffer should be taken into account.
An option could be to switch from strncat() to strlcat() which does the
correct test to avoid such an overflow.
However, this actually looks as dead code, because 'defcmd_in_progress'
can't be true here.
See a more detailed explanation at [1].
[1]: https://lore.kernel.org/all/CAD=FV=WSh7wKN7Yp-3wWiDgX4E3isQ8uh0LCzTmd1v9Cg9j+nQ@mail.gmail.com/
Fixes: 5d5314d679 ("kdb: core for kgdb back end (1 of 2)")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit ad99b5105c0823ff02126497f4366e6a8009453e ]
Currently the PROMPT variable could be abused to provoke the printf()
machinery to read outside the current stack frame. Normally this
doesn't matter becaues md is already a much better tool for reading
from memory.
However the md command can be disabled by not setting KDB_ENABLE_MEM_READ.
Let's also prevent PROMPT from being modified in these circumstances.
Whilst adding a comment to help future code reviewers we also remove
the #ifdef where PROMPT in consumed. There is no problem passing an
unused (0) to snprintf when !CONFIG_SMP.
argument
Reported-by: Wang Xiayang <xywang.sjtu@sjtu.edu.cn>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Stable-dep-of: 4f41d30cd6dc ("kdb: Fix a potential buffer overflow in kdb_local()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit eadb2f47a3ced5c64b23b90fd2a3463f63726066 upstream.
KGDB and KDB allow read and write access to kernel memory, and thus
should be restricted during lockdown. An attacker with access to a
serial port (for example, via a hypervisor console, which some cloud
vendors provide over the network) could trigger the debugger so it is
important that the debugger respect the lockdown mode when/if it is
triggered.
Fix this by integrating lockdown into kdb's existing permissions
mechanism. Unfortunately kgdb does not have any permissions mechanism
(although it certainly could be added later) so, for now, kgdb is simply
and brutally disabled by immediately exiting the gdb stub without taking
any action.
For lockdowns established early in the boot (e.g. the normal case) then
this should be fine but on systems where kgdb has set breakpoints before
the lockdown is enacted than "bad things" will happen.
CVE: CVE-2022-21499
Co-developed-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 93f7a6d818deef69d0ba652d46bae6fbabbf365c upstream.
Currently kdb uses in_interrupt() to determine whether its library
code has been called from the kgdb trap handler or from a saner calling
context such as driver init. This approach is broken because
in_interrupt() alone isn't able to determine kgdb trap handler entry from
normal task context. This can happen during normal use of basic features
such as breakpoints and can also be trivially reproduced using:
echo g > /proc/sysrq-trigger
We can improve this by adding check for in_dbg_master() instead which
explicitly determines if we are running in debugger context.
Cc: stable@vger.kernel.org
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Link: https://lore.kernel.org/r/1611313556-4004-1-git-send-email-sumit.garg@linaro.org
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit d081a6e353168f15e63eb9e9334757f20343319f ]
Currently using forward search doesn't handle multi-line strings correctly.
The search routine replaces line breaks with \0 during the search and, for
regular searches ("help | grep Common\n"), there is code after the line
has been discarded or printed to replace the break character.
However during a pager search ("help\n" followed by "/Common\n") when the
string is matched we will immediately return to normal output and the code
that should restore the \n becomes unreachable. Fix this by restoring the
replaced character when we disable the search mode and update the comment
accordingly.
Fixes: fb6daa7520 ("kdb: Provide forward search at more prompt")
Link: https://lore.kernel.org/r/20200909141708.338273-1-daniel.thompson@linaro.org
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
strncmp(str, const, len) is error-prone.
We had better use newly introduced
str_has_prefix() instead of it.
Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
The strncpy() function may leave the destination string buffer
unterminated, better use strscpy() instead.
This fixes the following warning with gcc 8.2:
kernel/debug/kdb/kdb_io.c: In function 'kdb_getstr':
kernel/debug/kdb/kdb_io.c:449:3: warning: 'strncpy' specified bound 256 equals destination size [-Wstringop-truncation]
strncpy(kdb_prompt_str, prompt, CMD_BUFLEN);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Signed-off-by: Wenlin Kang <wenlin.kang@windriver.com>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
The "whichcpu" comes from argv[3]. The cpu_online() macro looks up the
cpu in a bitmap of online cpus, but if the value is too high then it
could read beyond the end of the bitmap and possibly Oops.
Fixes: 5d5314d679 ("kdb: core for kgdb back end (1 of 2)")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
If you drop into kdb and type "summary", it prints out a line that
says this:
ccversion CCVERSION
...and I don't mean that it actually prints out the version of the C
compiler. It literally prints out the string "CCVERSION".
The version of the C Compiler is already printed at boot up and it
doesn't seem useful to replicate this in kdb. Let's just delete it.
We can also delete the bit of the Makefile that called the C compiler
in an attempt to pass this into kdb. This will remove one extra call
to the C compiler at Makefile parse time and (very slightly) speed up
builds.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
The strcpy() function is being deprecated. Replace it by the safer
strscpy() and fix the following Coverity warning:
"You might overrun the 129-character fixed-size string ks_namebuf
by copying name without checking the length."
Addresses-Coverity-ID: 138995 ("Copy into fixed size buffer")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
defcmd_in_progress is the state trace for command group processing
- within a command group or not - usable is an indicator if a command
set is valid (allocated/non-empty) - so use a bool for those binary
indication here.
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
If you have a CPU that fails to round up and then run 'btc' you'll end
up crashing in kdb becaue we dereferenced NULL. Let's add a check.
It's wise to also set the task to NULL when leaving the debugger so
that if we fail to round up on a later entry into the debugger we
won't backtrace a stale task.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.
Notice that in this particular case, I replaced the code comments with
a proper "fall through" annotation, which is what GCC is expecting
to find.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.
Notice that in this particular case, I replaced the code comments with
a proper "fall through" annotation, which is what GCC is expecting
to find.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Replace the whole switch statement with a for loop. This makes the
code clearer and easy to read.
This also addresses the following Coverity warnings:
Addresses-Coverity-ID: 115090 ("Missing break in switch")
Addresses-Coverity-ID: 115091 ("Missing break in switch")
Addresses-Coverity-ID: 114700 ("Missing break in switch")
Suggested-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
[daniel.thompson@linaro.org: Tiny grammar change in description]
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
gcc 8.1.0 warns with:
kernel/debug/kdb/kdb_support.c: In function ‘kallsyms_symbol_next’:
kernel/debug/kdb/kdb_support.c:239:4: warning: ‘strncpy’ specified bound depends on the length of the source argument [-Wstringop-overflow=]
strncpy(prefix_name, name, strlen(name)+1);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/debug/kdb/kdb_support.c:239:31: note: length computed here
Use strscpy() with the destination buffer size, and use ellipses when
displaying truncated symbols.
v2: Use strscpy()
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Jonathan Toppins <jtoppins@redhat.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: kgdb-bugreport@lists.sourceforge.net
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Since commit ad67b74d24 ("printk: hash addresses printed with %p"),
all pointers printed with %p are printed with hashed addresses
instead of real addresses in order to avoid leaking addresses in
dmesg and syslog. But this applies to kdb too, with is unfortunate:
Entering kdb (current=0x(ptrval), pid 329) due to Keyboard Entry
kdb> ps
15 sleeping system daemon (state M) processes suppressed,
use 'ps A' to see all.
Task Addr Pid Parent [*] cpu State Thread Command
0x(ptrval) 329 328 1 0 R 0x(ptrval) *sh
0x(ptrval) 1 0 0 0 S 0x(ptrval) init
0x(ptrval) 3 2 0 0 D 0x(ptrval) rcu_gp
0x(ptrval) 4 2 0 0 D 0x(ptrval) rcu_par_gp
0x(ptrval) 5 2 0 0 D 0x(ptrval) kworker/0:0
0x(ptrval) 6 2 0 0 D 0x(ptrval) kworker/0:0H
0x(ptrval) 7 2 0 0 D 0x(ptrval) kworker/u2:0
0x(ptrval) 8 2 0 0 D 0x(ptrval) mm_percpu_wq
0x(ptrval) 10 2 0 0 D 0x(ptrval) rcu_preempt
The whole purpose of kdb is to debug, and for debugging real addresses
need to be known. In addition, data displayed by kdb doesn't go into
dmesg.
This patch replaces all %p by %px in kdb in order to display real
addresses.
Fixes: ad67b74d24 ("printk: hash addresses printed with %p")
Cc: <stable@vger.kernel.org>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
On a powerpc 8xx, 'btc' fails as follows:
Entering kdb (current=0x(ptrval), pid 282) due to Keyboard Entry
kdb> btc
btc: cpu status: Currently on cpu 0
Available cpus: 0
kdb_getarea: Bad address 0x0
when booting the kernel with 'debug_boot_weak_hash', it fails as well
Entering kdb (current=0xba99ad80, pid 284) due to Keyboard Entry
kdb> btc
btc: cpu status: Currently on cpu 0
Available cpus: 0
kdb_getarea: Bad address 0xba99ad80
On other platforms, Oopses have been observed too, see
https://github.com/linuxppc/linux/issues/139
This is due to btc calling 'btt' with %p pointer as an argument.
This patch replaces %p by %px to get the real pointer value as
expected by 'btt'
Fixes: ad67b74d24 ("printk: hash addresses printed with %p")
Cc: <stable@vger.kernel.org>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
There are several definitions of those functions/macros in places that
mess with fixed-point load averages. Provide an official version.
[akpm@linux-foundation.org: fix missed conversion in block/blk-iolatency.c]
Link: http://lkml.kernel.org/r/20180828172258.3185-5-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Tested-by: Daniel Drake <drake@endlessm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* minor regression test cleanup
* formatting fixes for end user use of kdb
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Merge tag 'for_linus-4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb
Pull kdb updates from Jason Wessel:
- fix 2032 time access issues and new compiler warnings
- minor regression test cleanup
- formatting fixes for end user use of kdb
* tag 'for_linus-4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb:
kdb: use memmove instead of overlapping memcpy
kdb: use ktime_get_mono_fast_ns() instead of ktime_get_ts()
kdb: bl: don't use tab character in output
kdb: drop newline in unknown command output
kdb: make "mdr" command repeat
kdb: use __ktime_get_real_seconds instead of __current_kernel_time
misc: kgdbts: Display progress of asynchronous tests
gcc discovered that the memcpy() arguments in kdbnearsym() overlap, so
we should really use memmove(), which is defined to handle that correctly:
In function 'memcpy',
inlined from 'kdbnearsym' at /git/arm-soc/kernel/debug/kdb/kdb_support.c:132:4:
/git/arm-soc/include/linux/string.h:353:9: error: '__builtin_memcpy' accessing 792 bytes at offsets 0 and 8 overlaps 784 bytes at offset 8 [-Werror=restrict]
return __builtin_memcpy(p, q, size);
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
The kdb code will print the monotonic time by ktime_get_ts(), but
the ktime_get_ts() will be protected by a sequence lock, that will
introduce one deadlock risk if the lock was already held in the
context from which we entered the debugger.
Thus we can use the ktime_get_mono_fast_ns() to get the monotonic
time, which is NMI safe access to clock monotonic. Moreover we can
remove the 'struct timespec', which is not y2038 safe.
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
The "bl" (list breakpoints) command prints a '\t' (tab) character
in its output, but on a console (video device), that just prints
some odd graphics character. Instead of printing a tab character,
just align the output with spaces.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: kgdb-bugreport@lists.sourceforge.net
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
When an unknown command is entered, kdb prints "Unknown kdb command:"
and then the unknown text, including the newline character. This
causes the ending single-quote mark to be printed on the next line
by itself, so just change the ending newline character to a null
character (end of string) so that it won't be "printed."
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: kgdb-bugreport@lists.sourceforge.net
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
The "mdr" command should repeat (continue) when only Enter/Return
is pressed, so make it do so.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: kgdb-bugreport@lists.sourceforge.net
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
kdb is the only user of the __current_kernel_time() interface, which is
not y2038 safe and should be removed at some point.
The kdb code also goes to great lengths to print the time in a
human-readable format from 'struct timespec', again using a non-y2038-safe
re-implementation of the generic time_to_tm() code.
Using __current_kernel_time() here is necessary since the regular
accessors that require a sequence lock might hang when called during the
xtime update. However, this is safe in the particular case since kdb is
only interested in the tv_sec field that is updated atomically.
In order to make this y2038-safe, I'm converting the code to the generic
time64_to_tm helper, but that introduces the problem that we have no
interface like __current_kernel_time() that provides a 64-bit timestamp
in a lockless, safe and architecture-independent way. I have multiple
ideas for how to solve that:
- __ktime_get_real_seconds() is lockless, but can return
incorrect results on 32-bit architectures in the special case that
we are in the process of changing the time across the epoch, either
during the timer tick that overflows the seconds in 2038, or while
calling settimeofday.
- ktime_get_real_fast_ns() would work in this context, but does
require a call into the clocksource driver to return a high-resolution
timestamp. This may have undesired side-effects in the debugger,
since we want to limit the interactions with the rest of the kernel.
- Adding a ktime_get_real_fast_seconds() based on tk_fast_mono
plus tkr->base_real without the tk_clock_read() delta. Not sure about
the value of adding yet another interface here.
- Changing the existing ktime_get_real_seconds() to use
tk_fast_mono on 32-bit architectures rather than xtime_sec. I think
this could work, but am not entirely sure if this is an improvement.
I picked the first of those for simplicity here. It's technically
not correct but probably good enough as the time is only used for the
debugging output and the race will likely never be hit in practice.
Another downside is having to move the declaration into a public header
file.
Let me know if anyone has a different preference.
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patchwork.kernel.org/patch/9775309/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
- Rename from kdb_send_sig_info to kdb_send_sig
As there is no meaningful siginfo sent
- Use SEND_SIG_PRIV instead of generating a siginfo for a kdb
signal. The generated siginfo had a bogus rationale and was
not correct in the face of pid namespaces. SEND_SIG_PRIV
is simpler and actually correct.
- As the code grabs siglock just send the signal with siglock
held instead of dropping siglock and attempting to grab it again.
- Move the sig_valid test into kdb_kill where it can generate
a good error message.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
kallsyms_symbol_next() returns a boolean (true on success). Currently
kdb_read() tests the return value with an inequality that
unconditionally evaluates to true.
This is fixed in the obvious way and, since the conditional branch is
supposed to be unreachable, we also add a WARN_ON().
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
We are going to split <linux/sched/debug.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/debug.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/stat.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/stat.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/signal.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/loadavg.h> out of <linux/sched.h>, which
will have to be picked up from a couple of .c files.
Create a trivial placeholder <linux/sched/topology.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
kdb_trap_printk allows to pass normal printk() messages to kdb via
vkdb_printk(). For example, it is used to get backtrace using the
classic show_stack(), see kdb_show_stack().
vkdb_printf() tries to avoid a potential infinite loop by disabling the
trap. But this approach is racy, for example:
CPU1 CPU2
vkdb_printf()
// assume that kdb_trap_printk == 0
saved_trap_printk = kdb_trap_printk;
kdb_trap_printk = 0;
kdb_show_stack()
kdb_trap_printk++;
Problem1: Now, a nested printk() on CPU0 calls vkdb_printf()
even when it should have been disabled. It will not
cause a deadlock but...
// using the outdated saved value: 0
kdb_trap_printk = saved_trap_printk;
kdb_trap_printk--;
Problem2: Now, kdb_trap_printk == -1 and will stay like this.
It means that all messages will get passed to kdb from
now on.
This patch removes the racy saved_trap_printk handling. Instead, the
recursion is prevented by a check for the locked CPU.
The solution is still kind of racy. A non-related printk(), from
another process, might get trapped by vkdb_printf(). And the wanted
printk() might not get trapped because kdb_printf_cpu is assigned. But
this problem existed even with the original code.
A proper solution would be to get_cpu() before setting kdb_trap_printk
and trap messages only from this CPU. I am not sure if it is worth the
effort, though.
In fact, the race is very theoretical. When kdb is running any of the
commands that use kdb_trap_printk there is a single active CPU and the
other CPUs should be in a holding pen inside kgdb_cpu_enter().
The only time this is violated is when there is a timeout waiting for
the other CPUs to report to the holding pen.
Finally, note that the situation is a bit schizophrenic. vkdb_printf()
explicitly allows recursion but only from KDB code that calls
kdb_printf() directly. On the other hand, the generic printk()
recursion is not allowed because it might cause an infinite loop. This
is why we could not hide the decision inside vkdb_printf() easily.
Link: http://lkml.kernel.org/r/1480412276-16690-4-git-send-email-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kdb_printf_lock does not prevent other CPUs from entering the critical
section because it is ignored when KDB_STATE_PRINTF_LOCK is set.
The problematic situation might look like:
CPU0 CPU1
vkdb_printf()
if (!KDB_STATE(PRINTF_LOCK))
KDB_STATE_SET(PRINTF_LOCK);
spin_lock_irqsave(&kdb_printf_lock, flags);
vkdb_printf()
if (!KDB_STATE(PRINTF_LOCK))
BANG: The PRINTF_LOCK state is set and CPU1 is entering the critical
section without spinning on the lock.
The problem is that the code tries to implement locking using two state
variables that are not handled atomically. Well, we need a custom
locking because we want to allow reentering the critical section on the
very same CPU.
Let's use solution from Petr Zijlstra that was proposed for a similar
scenario, see
https://lkml.kernel.org/r/20161018171513.734367391@infradead.org
This patch uses the same trick with cmpxchg(). The only difference is
that we want to handle only recursion from the same context and
therefore we disable interrupts.
In addition, KDB_STATE_PRINTF_LOCK is removed. In fact, we are not able
to set it a non-racy way.
Link: http://lkml.kernel.org/r/1480412276-16690-3-git-send-email-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kdb_event state variable is only set but never checked in the kernel
code.
http://www.spinics.net/lists/kdb/msg01733.html suggests that this
variable affected WARN_CONSOLE_UNLOCKED() in the original
implementation. But this check never went upstream.
The semantic is unclear and racy. The value is updated after the
kdb_printf_lock is acquired and after it is released. It should be
symmetric at minimum. The value should be manipulated either inside or
outside the locked area.
Fortunately, it seems that the original function is gone and we could
simply remove the state variable.
Link: http://lkml.kernel.org/r/1480412276-16690-2-git-send-email-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Suggested-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 4bcc595ccd ("printk: reinstate KERN_CONT for printing
continuation lines") allows to define more message headers for a single
message. The motivation is that continuous lines might get mixed.
Therefore it make sense to define the right log level for every piece of
a cont line.
This patch introduces printk_skip_headers() that will skip all headers
and uses it in the kdb code instead of printk_skip_level().
This approach helps to fix other printk_skip_level() users
independently.
Link: http://lkml.kernel.org/r/1478695291-12169-3-git-send-email-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Joe Perches <joe@perches.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: David Sterba <dsterba@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It may be useful to debug writes to the readonly sections of memory,
so provide a cmdline "rodata=off" to allow for this. This can be
expanded in the future to support "log" and "write" modes, but that
will need to be architecture-specific.
This also makes KDB software breakpoints more usable, as read-only
mappings can now be disabled on any kernel.
Suggested-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Brown <david.brown@linaro.org>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Emese Revfy <re.emese@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathias Krause <minipli@googlemail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: PaX Team <pageexec@freemail.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-hardening@lists.openwall.com
Cc: linux-arch <linux-arch@vger.kernel.org>
Link: http://lkml.kernel.org/r/1455748879-21872-3-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Makes it easier to handle init vs core cleanly, though the change is
fairly invasive across random architectures.
It simplifies the rbtree code immediately, however, while keeping the
core data together in the same cachline (now iff the rbtree code is
enabled).
Acked-by: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
All current callers of kdb_getstr() can pass constant pointers via the
prompt argument. This patch adds a const qualification to make explicit
the fact that this is safe.
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Currently kdb allows the output of comamnds to be filtered using the
| grep feature. This is useful but does not permit the output emitted
shortly after a string match to be examined without wading through the
entire unfiltered output of the command. Such a feature is particularly
useful to navigate function traces because these traces often have a
useful trigger string *before* the point of interest.
This patch reuses the existing filtering logic to introduce a simple
forward search to kdb that can be triggered from the more prompt.
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Currently when the "| grep" feature is used to filter the output of a
command then the prompt is not displayed for the subsequent command.
Likewise any characters typed by the user are also not echoed to the
display. This rather disconcerting problem eventually corrects itself
when the user presses Enter and the kdb_grepping_flag is cleared as
kdb_parse() tries to make sense of whatever they typed.
This patch resolves the problem by moving the clearing of this flag
from the middle of command processing to the beginning.
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
