This is a note to let you know that I've just added the patch titled
afs: Fix dynamic root getattr
to the 5.18-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:
afs-fix-dynamic-root-getattr.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 94d5838602655a70aab2ba97885936e81cf24497
Author: David Howells <dhowells@xxxxxxxxxx>
Date: Tue Jun 21 15:59:57 2022 +0100
afs: Fix dynamic root getattr
[ Upstream commit cb78d1b5efffe4cf97e16766329dd7358aed3deb ]
The recent patch to make afs_getattr consult the server didn't account
for the pseudo-inodes employed by the dynamic root-type afs superblock
not having a volume or a server to access, and thus an oops occurs if
such a directory is stat'd.
Fix this by checking to see if the vnode->volume pointer actually points
anywhere before following it in afs_getattr().
This can be tested by stat'ing a directory in /afs. It may be
sufficient just to do "ls /afs" and the oops looks something like:
BUG: kernel NULL pointer dereference, address: 0000000000000020
...
RIP: 0010:afs_getattr+0x8b/0x14b
...
Call Trace:
<TASK>
vfs_statx+0x79/0xf5
vfs_fstatat+0x49/0x62
Fixes: 2aeb8c86d499 ("afs: Fix afs_getattr() to refetch file status if callback break occurred")
Reported-by: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Reviewed-by: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
Tested-by: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
cc: linux-afs@xxxxxxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/165408450783.1031787.7941404776393751186.stgit@xxxxxxxxxxxxxxxxxxxxxx/
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 22811e9eacf5..c4c9f6dff0a2 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -745,7 +745,8 @@ int afs_getattr(struct user_namespace *mnt_userns, const struct path *path,
_enter("{ ino=%lu v=%u }", inode->i_ino, inode->i_generation);
- if (!(query_flags & AT_STATX_DONT_SYNC) &&
+ if (vnode->volume &&
+ !(query_flags & AT_STATX_DONT_SYNC) &&
!test_bit(AFS_VNODE_CB_PROMISED, &vnode->flags)) {
key = afs_request_key(vnode->volume->cell);
if (IS_ERR(key))
