linux-kernel - [PATCH 5.15 041/244] NFSv4/pnfs: Fix a use-after-free bug in open

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Date:   Tue, 23 Aug 2022 10:23:20 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Trond Myklebust <trond.myklebust@...merspace.com>
Subject: [PATCH 5.15 041/244] NFSv4/pnfs: Fix a use-after-free bug in open

From: Trond Myklebust <trond.myklebust@...merspace.com>

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@...merspace.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/nfs/nfs4proc.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -3106,12 +3106,13 @@ static int _nfs4_open_and_get_state(stru
 	}
 
 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;
 }