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

BugLink: https://bugs.launchpad.net/bugs/1990564
commit 2135e5d56278ffdb1c2e6d325dc6b87f669b9dac upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index b7ace88b7794816d7c06914698d78b3016643502..9b1c18a6b3e8bc69f1135f04566b0fc28362f18c 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -3110,12 +3110,13 @@ 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;
 }