From: David Howells dhowells@redhat.com
[ 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@auristor.com Signed-off-by: David Howells dhowells@redhat.com Reviewed-by: Marc Dionne marc.dionne@auristor.com Tested-by: Marc Dionne marc.dionne@auristor.com cc: linux-afs@lists.infradead.org Link: https://lore.kernel.org/r/165408450783.1031787.7941404776393751186.stgit@war... Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/afs/inode.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
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))