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 D31DF2561B3; Wed, 23 Apr 2025 15:14:40 +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=1745421280; cv=none; b=HHiv3UjShc4wOOv9Lrd9AmBkcfZMR0gpRgZr5QHfhrQEqSBzdEk87l/nbyv7e4+D5+4bs/nn3LBqbRPNKCxDHW7WVu798TtOjwia4pSZWOMGv4YDYpKdlXz41uvV38XkbqX2CPfFBUYpZ/8SSj3wv+OgVWqRcW2npK+a30PF1bE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745421280; c=relaxed/simple; bh=5E3eABZWuq4fnArr8cPRmxLWaESHJOPdbYef9gZSpaA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=eS7tIBrgnXLLiBErEO3S0nxw51GFK90xiXCvjZM1LV5oQkf7g+k+hpK7LnrOSvdlgZokUNnOwQU63UbQ4hX372FYcde2vaoM/DLy9c4RHFxwGw9X3V/3opmljIc4908FH663sSOBowDy5aknJsAylj0HZFZV1J62VbhlG8aoZ5s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0jGM1VM+; 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="0jGM1VM+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 00C8BC4CEE2; Wed, 23 Apr 2025 15:14:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1745421280; bh=5E3eABZWuq4fnArr8cPRmxLWaESHJOPdbYef9gZSpaA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0jGM1VM+xxF0KMbrmEIZBiFk00WG3973pLE8iVuH/7NoT3csD67PGdvhAIyiCje1C F/3FP7Yk8q37ZXj1aoRWuGg6wxX68hbc0os2EaXHpsdBMXZxOpA4tFmrToIffYDusx X9ygQuGawq44GfB/m8t++PBLlROMfCvWHNeEqUM8= 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 6.1 123/291] mptcp: fix NULL pointer in can_accept_new_subflow Date: Wed, 23 Apr 2025 16:41:52 +0200 Message-ID: <20250423142629.427113211@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250423142624.409452181@linuxfoundation.org> References: <20250423142624.409452181@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-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 @@ -643,8 +643,6 @@ 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, @@ -739,12 +737,8 @@ static struct sock *subflow_syn_recv_soc } 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: @@ -793,6 +787,13 @@ 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;