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From: cel@kernel.org
To: Neil Brown <neilb@suse.de>, Jeff Layton <jlayton@kernel.org>,
	Olga Kornievskaia <okorniev@redhat.com>,
	Dai Ngo <dai.ngo@oracle.com>, Tom Talpey <tom@talpey.com>
Cc: <linux-nfs@vger.kernel.org>, Chuck Lever <chuck.lever@oracle.com>
Subject: [RFC PATCH 3/6] NFSD: Prevent NULL dereference in nfsd4_process_cb_update()
Date: Thu, 17 Oct 2024 11:03:53 -0400	[thread overview]
Message-ID: <20241017150349.216096-11-cel@kernel.org> (raw)
In-Reply-To: <20241017150349.216096-8-cel@kernel.org>

From: Chuck Lever <chuck.lever@oracle.com>

@ses is initialized to NULL. If __nfsd4_find_backchannel() finds no
available backchannel session, setup_callback_client() will try to
dereference @ses and segfault.

Fixes: dcbeaa68dbbd ("nfsd4: allow backchannel recovery")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfsd/nfs4callback.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index d86a7b983785..2e18f635078f 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -1500,6 +1500,8 @@ static void nfsd4_process_cb_update(struct nfsd4_callback *cb)
 		ses = c->cn_session;
 	}
 	spin_unlock(&clp->cl_lock);
+	if (!c)
+		return;
 
 	err = setup_callback_client(clp, &conn, ses);
 	if (err) {
-- 
2.46.2


  parent reply	other threads:[~2024-10-17 15:04 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-10-17 15:03 [RFC PATCH 0/6] Fix nits found by static analysis cel
2024-10-17 15:03 ` [RFC PATCH 1/6] NFSD: Remove dead code in nfsd4_create_session() cel
2024-10-17 15:03 ` [RFC PATCH 2/6] NFSD: Remove a never-true comparison cel
2024-10-17 15:03 ` cel [this message]
2024-10-17 15:03 ` [RFC PATCH 4/6] NFSD: Remove unused results in nfsd4_encode_pathname4() cel
2024-10-17 15:03 ` [RFC PATCH 5/6] NFSD: Remove unused values from nfsd4_encode_components_esc() cel
2024-10-17 15:03 ` [RFC PATCH 6/6] NFSD: Cap the number of bytes copied by nfs4_reset_recoverydir() cel
2024-10-17 15:16 ` [RFC PATCH 0/6] Fix nits found by static analysis Jeff Layton

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