This is a note to let you know that I've just added the patch titled
fs/sysv: Null check to prevent null-ptr-deref bug
to the 6.4-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:
fs-sysv-null-check-to-prevent-null-ptr-deref-bug.patch
and it can be found in the queue-6.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit abf4a5eb10d8347e712f0985d965ff89d05a571f
Author: Prince Kumar Maurya <princekumarmaurya06@xxxxxxxxx>
Date: Tue May 30 18:31:41 2023 -0700
fs/sysv: Null check to prevent null-ptr-deref bug
[ Upstream commit ea2b62f305893992156a798f665847e0663c9f41 ]
sb_getblk(inode->i_sb, parent) return a null ptr and taking lock on
that leads to the null-ptr-deref bug.
Reported-by: syzbot+aad58150cbc64ba41bdc@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=aad58150cbc64ba41bdc
Signed-off-by: Prince Kumar Maurya <princekumarmaurya06@xxxxxxxxx>
Message-Id: <20230531013141.19487-1-princekumarmaurya06@xxxxxxxxx>
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/sysv/itree.c b/fs/sysv/itree.c
index b22764fe669c8..58d7f43a13712 100644
--- a/fs/sysv/itree.c
+++ b/fs/sysv/itree.c
@@ -145,6 +145,10 @@ static int alloc_branch(struct inode *inode,
*/
parent = block_to_cpu(SYSV_SB(inode->i_sb), branch[n-1].key);
bh = sb_getblk(inode->i_sb, parent);
+ if (!bh) {
+ sysv_free_block(inode->i_sb, branch[n].key);
+ break;
+ }
lock_buffer(bh);
memset(bh->b_data, 0, blocksize);
branch[n].bh = bh;
