From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4CE2021ABC1; Tue, 29 Apr 2025 17:46:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745948812; cv=none; b=clBgGhLzbfHJzy3OofIPHX4xmaPQ0mOZjm2nLCFNn77oVkTaP2ARxx/nO89l4ZE2XcVmtPCvdYJSJbQKd7kx5fifDiRYoBv4rawnxD6k23n6JoBhkTopDicGdzIbceBO0E2R8ScTyDA4g03lN85mSY6RnNvF6vgloGYoXmYhTFc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745948812; c=relaxed/simple; bh=oY4XQ01Y24H64bCmNN9upXH3TSMjsm7ODa+kgkLJI60=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OqJDoE1hq1/cmujcFVsheD8ADrdtLnNnoQtmsZ0NxbJz7xhoAOBwJcYWZM/+S8ekiV1SiAwOQfqykDNBtXBWYDOdoPxVBKpicwjwYsadeWHYO0Yju44+6iIFMhL3UMgU+ND9AcpNwjwWau3pBIrxNYl/7ZreCFMAHSlj31YbCsQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=wt6YmRmN; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="wt6YmRmN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CCD23C4CEE3; Tue, 29 Apr 2025 17:46:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1745948812; bh=oY4XQ01Y24H64bCmNN9upXH3TSMjsm7ODa+kgkLJI60=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wt6YmRmN7ZEoylbM+H909pRGCZlHwOxpYwBi9k7REKkHoGhMha92R0jwhn6ffKntK k5Br+T+NCMWBoLWe/QJgFk6U6vcyqP0L1VeBReqHpFHoDbKC687pTuVWtxjUqTcwiS 7pLPzESgo11fCqDDv3iyLZjc1hMMVW5g9VyTpSuk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Paolo Abeni , Gang Yan , "Matthieu Baerts (NGI0)" , Jakub Kicinski Subject: [PATCH 5.15 094/373] mptcp: fix NULL pointer in can_accept_new_subflow Date: Tue, 29 Apr 2025 18:39:31 +0200 Message-ID: <20250429161127.024079316@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250429161123.119104857@linuxfoundation.org> References: <20250429161123.119104857@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Gang Yan commit 443041deb5ef6a1289a99ed95015ec7442f141dc upstream. When testing valkey benchmark tool with MPTCP, the kernel panics in 'mptcp_can_accept_new_subflow' because subflow_req->msk is NULL. Call trace: mptcp_can_accept_new_subflow (./net/mptcp/subflow.c:63 (discriminator 4)) (P) subflow_syn_recv_sock (./net/mptcp/subflow.c:854) tcp_check_req (./net/ipv4/tcp_minisocks.c:863) tcp_v4_rcv (./net/ipv4/tcp_ipv4.c:2268) ip_protocol_deliver_rcu (./net/ipv4/ip_input.c:207) ip_local_deliver_finish (./net/ipv4/ip_input.c:234) ip_local_deliver (./net/ipv4/ip_input.c:254) ip_rcv_finish (./net/ipv4/ip_input.c:449) ... According to the debug log, the same req received two SYN-ACK in a very short time, very likely because the client retransmits the syn ack due to multiple reasons. Even if the packets are transmitted with a relevant time interval, they can be processed by the server on different CPUs concurrently). The 'subflow_req->msk' ownership is transferred to the subflow the first, and there will be a risk of a null pointer dereference here. This patch fixes this issue by moving the 'subflow_req->msk' under the `own_req == true` conditional. Note that the !msk check in subflow_hmac_valid() can be dropped, because the same check already exists under the own_req mpj branch where the code has been moved to. Fixes: 9466a1ccebbe ("mptcp: enable JOIN requests even if cookies are in use") Cc: stable@vger.kernel.org Suggested-by: Paolo Abeni Signed-off-by: Gang Yan Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20250328-net-mptcp-misc-fixes-6-15-v1-1-34161a482a7f@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/mptcp/subflow.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -589,8 +589,6 @@ static bool subflow_hmac_valid(const str subflow_req = mptcp_subflow_rsk(req); msk = subflow_req->msk; - if (!msk) - return false; subflow_generate_hmac(msk->remote_key, msk->local_key, subflow_req->remote_nonce, @@ -716,12 +714,8 @@ static struct sock *subflow_syn_recv_soc fallback = true; } else if (subflow_req->mp_join) { mptcp_get_options(skb, &mp_opt); - if (!(mp_opt.suboptions & OPTION_MPTCP_MPJ_ACK) || - !subflow_hmac_valid(req, &mp_opt) || - !mptcp_can_accept_new_subflow(subflow_req->msk)) { - SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC); + if (!(mp_opt.suboptions & OPTION_MPTCP_MPJ_ACK)) fallback = true; - } } create_child: @@ -787,6 +781,13 @@ create_child: subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT); goto dispose_child; } + + if (!subflow_hmac_valid(req, &mp_opt) || + !mptcp_can_accept_new_subflow(subflow_req->msk)) { + SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC); + subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT); + goto dispose_child; + } /* move the msk reference ownership to the subflow */ subflow_req->msk = NULL;