Fix afs_atcell_get_link() to check if the workstation cell is unset before
doing the RCU pathwalk bit where we dereference that.
Fixes: 823869e1e616 ("afs: Fix afs_atcell_get_link() to handle RCU pathwalk")
Reported-by: syzbot+76a6f18e3af82e84f264@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Tested-by: syzbot+76a6f18e3af82e84f264@xxxxxxxxxxxxxxxxxxxxxxxxx
cc: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
cc: linux-afs@xxxxxxxxxxxxxxxxxxx
cc: linux-fsdevel@xxxxxxxxxxxxxxx
---
fs/afs/dynroot.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/afs/dynroot.c b/fs/afs/dynroot.c
index 9732a1e17db3..691e0ae607a1 100644
--- a/fs/afs/dynroot.c
+++ b/fs/afs/dynroot.c
@@ -210,6 +210,9 @@ static const char *afs_atcell_get_link(struct dentry *dentry, struct inode *inod
const char *name;
bool dotted = vnode->fid.vnode == 3;
+ if (!rcu_access_pointer(net->ws_cell))
+ return ERR_PTR(-ENOENT);
+
if (!dentry) {
/* We're in RCU-pathwalk. */
cell = rcu_dereference(net->ws_cell);
@@ -221,9 +224,6 @@ static const char *afs_atcell_get_link(struct dentry *dentry, struct inode *inod
return name;
}
- if (!rcu_access_pointer(net->ws_cell))
- return ERR_PTR(-ENOENT);
-
down_read(&net->cells_lock);
cell = rcu_dereference_protected(net->ws_cell, lockdep_is_held(&net->cells_lock));
