This is a note to let you know that I've just added the patch titled
FS: JFS: Fix null-ptr-deref Read in txBegin
to the 4.19-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:
fs-jfs-fix-null-ptr-deref-read-in-txbegin.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit f81faa8296c2f86d2d0356d97484a1d430e38676
Author: Immad Mir <mirimmad17@xxxxxxxxx>
Date: Fri Jun 23 19:14:01 2023 +0530
FS: JFS: Fix null-ptr-deref Read in txBegin
[ Upstream commit 47cfdc338d674d38f4b2f22b7612cc6a2763ba27 ]
Syzkaller reported an issue where txBegin may be called
on a superblock in a read-only mounted filesystem which leads
to NULL pointer deref. This could be solved by checking if
the filesystem is read-only before calling txBegin, and returning
with appropiate error code.
Reported-By: syzbot+f1faa20eec55e0c8644c@xxxxxxxxxxxxxxxxxxxxxxxxx
Link: https://syzkaller.appspot.com/bug?id=be7e52c50c5182cc09a09ea6fc456446b2039de3
Signed-off-by: Immad Mir <mirimmad17@xxxxxxxxx>
Signed-off-by: Dave Kleikamp <dave.kleikamp@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/jfs/namei.c b/fs/jfs/namei.c
index 14528c0ffe635..c2c439acbb780 100644
--- a/fs/jfs/namei.c
+++ b/fs/jfs/namei.c
@@ -811,6 +811,11 @@ static int jfs_link(struct dentry *old_dentry,
if (rc)
goto out;
+ if (isReadOnly(ip)) {
+ jfs_error(ip->i_sb, "read-only filesystem\n");
+ return -EROFS;
+ }
+
tid = txBegin(ip->i_sb, 0);
mutex_lock_nested(&JFS_IP(dir)->commit_mutex, COMMIT_MUTEX_PARENT);
