ACPR/android_system_core
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

init: snapuserd: Fix ranges for mlock()

Browse source 
It cannot be assumed that file mappings in /proc/<pid>/maps will be
completely backed by the underlying file. [1]

Use MappedFileSize() to deduce the correct ranges for the mlock()
calls when locking system pages in the OTA path.

While at it also clean up the some unreachable code (mlockall()),
and improve error logging.

[1] SIGBUS at https://man7.org/linux/man-pages/man2/mmap.2.html#RETURN_VALUE

Test: Incremental OTA
Bug: 324952273
Change-Id: Ia2ab150e1b8de8c638f5b1acc1de83deb7ac5cff
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
This commit is contained in:
Kalesh Singh 2024-02-14 17:03:01 -08:00
parent 8097002e09
commit f90de49e0e
1 changed files with 5 additions and 7 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

12
init/snapuserd_transition.cpp
View file

@ -195,22 +195,20 @@ static void LockAllSystemPages() {
return;
}
auto start = reinterpret_cast<const void*>(map.start);
auto len = map.end - map.start;
uint64_t len = android::procinfo::MappedFileSize(map);
if (!len) {
return;
}
if (mlock(start, len) < 0) {
LOG(ERROR) << "mlock failed, " << start << " for " << len << " bytes.";
PLOG(ERROR) << "\"" << map.name << "\": mlock(" << start << ", " << len
<< ") failed: pgoff = " << map.pgoff;
ok = false;
}
};
if (!android::procinfo::ReadProcessMaps(getpid(), callback) || !ok) {
LOG(FATAL) << "Could not process /proc/" << getpid() << "/maps file for init, "
<< "falling back to mlockall().";
if (mlockall(MCL_CURRENT) < 0) {
LOG(FATAL) << "mlockall failed";
}
LOG(FATAL) << "Could not process /proc/" << getpid() << "/maps file for init";
}
}