NFSv4/pnfs: Fix a use-after-free bug in open

If someone cancels the open RPC call, then we must not try to free
either the open slot or the layoutget operation arguments, since they
are likely still in use by the hung RPC call.

Fixes: 6949493884fe ("NFSv4: Don't hold the layoutget locks across multiple RPC calls")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 2d7c14ade1932f71ebfb20c14b8830db81ae69df..3ed14a2a84a4450ab8d4f75fe5b05e204c6bc19f 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -3096,12 +3096,13 @@ static int _nfs4_open_and_get_state(struct nfs4_opendata *opendata,
        }
 
 out:
-       if (opendata->lgp) {
-               nfs4_lgopen_release(opendata->lgp);
-               opendata->lgp = NULL;
-       }
-       if (!opendata->cancelled)
+       if (!opendata->cancelled) {
+               if (opendata->lgp) {
+                       nfs4_lgopen_release(opendata->lgp);
+                       opendata->lgp = NULL;
+               }
                nfs4_sequence_free_slot(&opendata->o_res.seq_res);
+       }
        return ret;
 }