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From:   Jeff Layton <jlayton@kernel.org>
To:     chuck.lever@oracle.com
Cc:     linux-nfs@vger.kernel.org, kernel test robot <lkp@intel.com>,
        Dan Carpenter <error27@gmail.com>
Subject: [PATCH] nfsd: fix use-after-free in nfsd_file_do_acquire tracepoint
Date:   Sat,  5 Nov 2022 09:49:26 -0400
Message-Id: <20221105134926.23726-1-jlayton@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

When we fail to insert into the hashtable with a non-retryable error,
we'll free the object and then goto out_status. If the tracepoint is
enabled, it'll end up accessing the freed object when it tries to
grab the fields out of it.

Set nf to NULL after freeing it to avoid the issue.

Fixes: 243a5263014a ("nfsd: rework hashtable handling in nfsd_do_file_acquire")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 fs/nfsd/filecache.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index 687ab814b678..02c1454dfe50 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -1124,6 +1124,7 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
 		goto open_file;
 
 	nfsd_file_slab_free(&nf->nf_rcu);
+	nf = NULL;
 	if (ret == -EEXIST)
 		goto retry;
 	trace_nfsd_file_insert_err(rqstp, key.inode, may_flags, ret);
-- 
2.38.1