This is a note to let you know that I've just added the patch titled
xfs: fix mount failure crash on invalid iclog memory access
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
xfs-fix-mount-failure-crash-on-invalid-iclog-memory-.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 0f1b1b4d60400feda3564064aa7b02c54be7254b
Author: Brian Foster <bfoster@xxxxxxxxxx>
Date: Tue Dec 3 07:53:15 2019 -0800
xfs: fix mount failure crash on invalid iclog memory access
[ Upstream commit 798a9cada4694ca8d970259f216cec47e675bfd5 ]
syzbot (via KASAN) reports a use-after-free in the error path of
xlog_alloc_log(). Specifically, the iclog freeing loop doesn't
handle the case of a fully initialized ->l_iclog linked list.
Instead, it assumes that the list is partially constructed and NULL
terminated.
This bug manifested because there was no possible error scenario
after iclog list setup when the original code was added. Subsequent
code and associated error conditions were added some time later,
while the original error handling code was never updated. Fix up the
error loop to terminate either on a NULL iclog or reaching the end
of the list.
Reported-by: syzbot+c732f8644185de340492@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 641d07f30a27..7b0d9ad8cb1a 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1495,6 +1495,8 @@ xlog_alloc_log(
prev_iclog = iclog->ic_next;
kmem_free(iclog->ic_data);
kmem_free(iclog);
+ if (prev_iclog == log->l_iclog)
+ break;
}
out_free_log:
kmem_free(log);
