| Message ID | 20210509002029.nJEe-yuk4%akpm@linux-foundation.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | + squashfs-fix-divide-error-in-calculate_skip.patch added to -mm tree | expand |
--- a/fs/squashfs/file.c~squashfs-fix-divide-error-in-calculate_skip +++ a/fs/squashfs/file.c @@ -211,11 +211,11 @@ failure: * If the skip factor is limited in this way then the file will use multiple * slots. */ -static inline int calculate_skip(int blocks) +static inline int calculate_skip(u64 blocks) { - int skip = blocks / ((SQUASHFS_META_ENTRIES + 1) + u64 skip = blocks / ((SQUASHFS_META_ENTRIES + 1) * SQUASHFS_META_INDEXES); - return min(SQUASHFS_CACHED_BLKS - 1, skip + 1); + return min((u64) SQUASHFS_CACHED_BLKS - 1, skip + 1); }
The patch titled Subject: squashfs: fix divide error in calculate_skip() has been added to the -mm tree. Its filename is squashfs-fix-divide-error-in-calculate_skip.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/squashfs-fix-divide-error-in-calculate_skip.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/squashfs-fix-divide-error-in-calculate_skip.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Phillip Lougher <phillip@squashfs.org.uk> Subject: squashfs: fix divide error in calculate_skip() Sysbot has reported a "divide error" which has been identified as being caused by a corrupted file_size value within the file inode. This value has been corrupted to a much larger value than expected. Calculate_skip() is passed i_size_read(inode) >> msblk->block_log. Due to the file_size value corruption this overflows the int argument/variable in that function, leading to the divide error. This patch changes the function to use u64. This will accommodate any unexpectedly large values due to corruption. The value returned from calculate_skip() is clamped to be never more than SQUASHFS_CACHED_BLKS - 1, or 7. So file_size corruption does not lead to an unexpectedly large return result here. Link: https://lkml.kernel.org/r/20210507152618.9447-1-phillip@squashfs.org.uk Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Reported-by: <syzbot+e8f781243ce16ac2f962@syzkaller.appspotmail.com> Reported-by: <syzbot+7b98870d4fec9447b951@syzkaller.appspotmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> --- fs/squashfs/file.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)