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fastboot: fix --disable-verifiation error message

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There is an unclear error message if we run
`fastboot --disable-verification flash boot boot.img` on a
AVB-disabled device without a /vbmeta partition.

Error message:
  terminating with uncaught exception of type std::out_of_range: basic_string
  Aborted

This is because the buf->fd of the loaded boot.img is not reset,
before returning from function copy_boot_avb_footer().

Also reset some changes in copy_boot_avb_footer() from commit
If83f785e235569ee8ef0de2b37f11dbd2a9a71f4, to prevent the
unnecessary read of the boot vbmeta if no need to copy the
boot image avb footer.

Bug: 191903922
Test: `fastboot --disable-verification flash boot boot.img` on a device
      without /vbmeta and without setting BOARD_AVB_ENABLE to true.
Change-Id: If84f08f1b2e12c4c6ded5cafda2bd1d30e75c662
This commit is contained in:
Bowgo Tsai 2021-08-10 16:32:37 +08:00
parent 6e3f64e7d8
commit 671249a3d2
1 changed files with 21 additions and 10 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

31
fastboot/fastboot.cpp
View file

@ -941,7 +941,8 @@ static void rewrite_vbmeta_buffer(struct fastboot_buffer* buf, bool vbmeta_in_bo
// Tries to locate top-level vbmeta from boot.img footer.
uint64_t footer_offset = buf->sz - AVB_FOOTER_SIZE;
if (0 != data.compare(footer_offset, AVB_FOOTER_MAGIC_LEN, AVB_FOOTER_MAGIC)) {
die("Failed to find AVB_FOOTER at offset: %" PRId64, footer_offset);
die("Failed to find AVB_FOOTER at offset: %" PRId64 ", is BOARD_AVB_ENABLE true?",
footer_offset);
}
const AvbFooter* footer = reinterpret_cast<const AvbFooter*>(data.c_str() + footer_offset);
vbmeta_offset = be64toh(footer->vbmeta_offset);
@ -1021,6 +1022,24 @@ static void copy_boot_avb_footer(const std::string& partition, struct fastboot_b
return;
}
// If overflows and negative, it should be < buf->sz.
int64_t partition_size = static_cast<int64_t>(get_partition_size(partition));
if (partition_size == buf->sz) {
return;
}
// Some device bootloaders might not implement `fastboot getvar partition-size:boot[_a|_b]`.
// In this case, partition_size will be zero.
if (partition_size < buf->sz) {
fprintf(stderr,
"Warning: skip copying boot image avb footer"
" (boot partition size: %" PRId64 ", boot image size: %" PRId64 ").\n",
partition_size, buf->sz);
return;
}
// IMPORTANT: after the following read, we need to reset buf->fd before return (if not die).
// Because buf->fd will still be used afterwards.
std::string data;
if (!android::base::ReadFdToString(buf->fd, &data)) {
die("Failed reading from boot");
@ -1028,17 +1047,9 @@ static void copy_boot_avb_footer(const std::string& partition, struct fastboot_b
uint64_t footer_offset = buf->sz - AVB_FOOTER_SIZE;
if (0 != data.compare(footer_offset, AVB_FOOTER_MAGIC_LEN, AVB_FOOTER_MAGIC)) {
lseek(buf->fd.get(), 0, SEEK_SET); // IMPORTANT: resets buf->fd before return.
return;
}
// If overflows and negative, it should be < buf->sz.
int64_t partition_size = static_cast<int64_t>(get_partition_size(partition));
if (partition_size == buf->sz) {
return;
}
if (partition_size < buf->sz) {
die("boot partition is smaller than boot image");
}
unique_fd fd(make_temporary_fd("boot rewriting"));
if (!android::base::WriteStringToFd(data, fd)) {