[SRU][J][PATCH 1/1] xfs: add bounds checking to xlog_recover_process_data

[Massimiliano Pellizzer]

From: lei lu <llfamsec at gmail.com>

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 at gmail.com>
Reviewed-by: Dave Chinner <dchinner at redhat.com>
Reviewed-by: Darrick J. Wong <djwong at kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu at kernel.org>
(cherry picked from commit fb63435b7c7dc112b1ae1baea5486e0a6e27b196)
CVE-2024-41014
Signed-off-by: Massimiliano Pellizzer <massimiliano.pellizzer at canonical.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 825e585758bb0..83c28b641e9a7 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -2444,7 +2444,10 @@ 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,
-- 
2.51.0