From: lei lu llfamsec@gmail.com
[ Upstream commit fb63435b7c7dc112b1ae1baea5486e0a6e27b196 ]
There is a lack of verification of the space occupied by fixed members of xlog_op_header in the xlog_recover_process_data.
We can create a crafted image to trigger an out of bounds read by following these steps: 1) Mount an image of xfs, and do some file operations to leave records 2) Before umounting, copy the image for subsequent steps to simulate abnormal exit. Because umount will ensure that tail_blk and head_blk are the same, which will result in the inability to enter xlog_recover_process_data 3) Write a tool to parse and modify the copied image in step 2 4) Make the end of the xlog_op_header entries only 1 byte away from xlog_rec_header->h_size 5) xlog_rec_header->h_num_logops++ 6) Modify xlog_rec_header->h_crc
Fix: Add a check to make sure there is sufficient space to access fixed members of xlog_op_header.
Signed-off-by: lei lu llfamsec@gmail.com Reviewed-by: Dave Chinner dchinner@redhat.com Reviewed-by: Darrick J. Wong djwong@kernel.org Signed-off-by: Chandan Babu R chandanbabu@kernel.org Signed-off-by: Bin Lan bin.lan.cn@windriver.com --- fs/xfs/xfs_log_recover.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c index affe94356ed1..006a376c34b2 100644 --- a/fs/xfs/xfs_log_recover.c +++ b/fs/xfs/xfs_log_recover.c @@ -2439,7 +2439,10 @@ xlog_recover_process_data(
ohead = (struct xlog_op_header *)dp; dp += sizeof(*ohead); - ASSERT(dp <= end); + if (dp > end) { + xfs_warn(log->l_mp, "%s: op header overrun", __func__); + return -EFSCORRUPTED; + }
/* errors will abort recovery */ error = xlog_recover_process_ophdr(log, rhash, rhead, ohead,