From patchwork Sat Feb 10 12:50:54 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?R=C3=A9mi_Denis-Courmont?= X-Patchwork-Id: 13552238 X-Patchwork-Delegate: kuba@kernel.org Received: from ursule.remlab.net (vps-a2bccee9.vps.ovh.net [51.75.19.47]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 7332E47F42; Sat, 10 Feb 2024 12:56:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=51.75.19.47 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707569803; cv=none; b=t6SM8mmSo97pfDmtZYo25By1pRjV1ANsDgCq9QOJpbbO/fWYpcPcwVLczjVxxzFlM3ROxUoxCPdFIzvQzgdJpOHo8bUmRQUY+acOCp88ZAkpZZw5xoejKrUgMBAE8bNW1o2Pfw+mp1daNMPrAdQFR/E1BLX1oT1DbiIfRTrWUxs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707569803; c=relaxed/simple; bh=jTamXYQSY1bQylvKzgcgdRQfmjJ8/TU+GEYdw1q4oMw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Q4u2e4akCFqqBLax7i7QxT6EfOPqPydXM7MazLa6FKXlbSRB8frPKk3m2ogDYw9nho7dMs8eNo6vPzVQ2BoF6Ei1rxSx6wwKWlVNPwv35hTEU1R2XCTJTQ8Y3kS9qnGtMNf8FHf8/HPFNsV3MKzxInritAJCUStVSTCnaTPan0c= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=remlab.net; spf=pass smtp.mailfrom=remlab.net; arc=none smtp.client-ip=51.75.19.47 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=remlab.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=remlab.net Received: from basile.remlab.net (localhost [IPv6:::1]) by ursule.remlab.net (Postfix) with ESMTP id C1E2AC022E; Sat, 10 Feb 2024 14:50:54 +0200 (EET) From: =?utf-8?q?R=C3=A9mi_Denis-Courmont?= To: courmisch@gmail.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/2] phonet/pep: fix racy skb_queue_empty() use Date: Sat, 10 Feb 2024 14:50:54 +0200 Message-ID: <20240210125054.71391-2-remi@remlab.net> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240210125054.71391-1-remi@remlab.net> References: <20240210125054.71391-1-remi@remlab.net> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org From: Rémi Denis-Courmont The receive queues are protected by their respective spin-lock, not the socket lock. This could lead to skb_peek() unexpectedly returning NULL or a pointer to an already dequeued socket buffer. Signed-off-by: Rémi Denis-Courmont --- net/phonet/pep.c | 41 ++++++++++++++++++++++++++++++++--------- 1 file changed, 32 insertions(+), 9 deletions(-) diff --git a/net/phonet/pep.c b/net/phonet/pep.c index faba31f2eff2..3dd5f52bc1b5 100644 --- a/net/phonet/pep.c +++ b/net/phonet/pep.c @@ -917,6 +917,37 @@ static int pep_sock_enable(struct sock *sk, struct sockaddr *addr, int len) return 0; } +static unsigned int pep_first_packet_length(struct sock *sk) +{ + struct pep_sock *pn = pep_sk(sk); + struct sk_buff_head *q; + struct sk_buff *skb; + unsigned int len = 0; + bool found = false; + + if (sock_flag(sk, SOCK_URGINLINE)) { + q = &pn->ctrlreq_queue; + spin_lock_bh(&q->lock); + skb = skb_peek(q); + if (skb) { + len = skb->len; + found = true; + } + spin_unlock_bh(&q->lock); + } + + if (likely(!found)) { + q = &sk->sk_receive_queue; + spin_lock_bh(&q->lock); + skb = skb_peek(q); + if (skb) + len = skb->len; + spin_unlock_bh(&q->lock); + } + + return len; +} + static int pep_ioctl(struct sock *sk, int cmd, int *karg) { struct pep_sock *pn = pep_sk(sk); @@ -929,15 +960,7 @@ static int pep_ioctl(struct sock *sk, int cmd, int *karg) break; } - lock_sock(sk); - if (sock_flag(sk, SOCK_URGINLINE) && - !skb_queue_empty(&pn->ctrlreq_queue)) - *karg = skb_peek(&pn->ctrlreq_queue)->len; - else if (!skb_queue_empty(&sk->sk_receive_queue)) - *karg = skb_peek(&sk->sk_receive_queue)->len; - else - *karg = 0; - release_sock(sk); + *karg = pep_first_packet_length(sk); ret = 0; break;