From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-dy1-f169.google.com (mail-dy1-f169.google.com [74.125.82.169]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4907C1DFF0 for ; Sun, 7 Jun 2026 02:29:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.169 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780799374; cv=none; b=czw5xpoB/Hdf41rjcKw9Hp5b8D/LvRlWZa4+UJf+a21lK7E5LU39U24mGyzGwABH2+9HRxmGdV+oJKRgo6MVk5Q5y4ELzVGNR7LYIYyO0NYQsew10VF9u18fJ/5EtMYYgbxnei9WVcbusBM6SpxH4MZXF5bcsVYtv2KwilPGVtI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780799374; c=relaxed/simple; bh=KFttDkOliwmcP5f1eeHeMTTOB1TRDM1UIzNlFvpHUPs=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=DdhT+xgk7uX7xQRkFkB04AuOzJudolFDy3gc9HidM8k9zYJW/fcEbXg6oIlN1q1fSV/9csdBTuhTaCm4DAMO9txu8zPPl9/BMbAmihMcD9bcfZB/ZH2hSb8ROynwJ+mrT9jes1V0PzdpBgDKTsoav3gw2RAU483fuo0kI++JOH8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=openai.com; spf=pass smtp.mailfrom=openai.com; dkim=pass (1024-bit key) header.d=openai.com header.i=@openai.com header.b=OshPRVmk; arc=none smtp.client-ip=74.125.82.169 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=openai.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=openai.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=openai.com header.i=@openai.com header.b="OshPRVmk" Received: by mail-dy1-f169.google.com with SMTP id 5a478bee46e88-3045c195251so2841797eec.1 for ; Sat, 06 Jun 2026 19:29:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=openai.com; s=google; t=1780799372; x=1781404172; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=PoxGSzb5xtE4/aEsKv2bqeRMWeH9RXRvVT6vJPuOv3Q=; b=OshPRVmkH4wfGT3as5ZEX7a4n9UEi2gYmUzoL7xJ9EauDFvAtG1Iqfz40+g4hqjOgQ tV7jAPiUxsYwPmdG+AAt2CQF3Qa3mq+dh//ImVLZ/kQhqXZjtM3kfQOHy36BQEmmhVR0 7ymR+afFQUbsChc8kQk5iIRV31UO+xfck4YQU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780799372; x=1781404172; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=PoxGSzb5xtE4/aEsKv2bqeRMWeH9RXRvVT6vJPuOv3Q=; b=c5GmMn9OUI2go8E5E9kS8qnq4PrmXxJlTz/KILGCcc8FihYZplqZWxXXH4XYdABnPl L1pcbXK+BRVwQ9oSt1ixr61nBy4NCa+XSrApFIJm29INRqm1vCqUTitmi4XXnMb0YMda +46az8wS+rXWkbT2MV34MUUs5dREdUpu4iOvGPvbS9O1fNFjTjlJXd/oG+gs46BBbaRi KJpualYGxNgMxZrI2UvV+W8TM/i/d4X1HgGdsSc10GwaOuscElStdAS5bCLJFkvlEXDk fkJI+dlCp5LWMChnvjgs29OPj2Lf6KokGZ6ohHfCEbAJGSrtzQ6aHtNGVj7cmSB2bgfD IbGw== X-Gm-Message-State: AOJu0YzFQV0OIABsBU8ImOGI8zkj32ks2xHYgQi6shmj//+PpgGfD1tv eLrA483wDq3xaJ7gX419OahE8n6KCV+fQytKzEqTxxHQdz+vbPxt7yr3CXI6c0TT/WxE5zIv4B1 bjm5FMm8= X-Gm-Gg: Acq92OHqmwh8o8i79VUs4knFdsYWU5C2UfGzOwUJZBJqe+xv8UnqI2Ba4zYCP0Xn+jo UnvLuZpbXuiEgQQhnl3MRIB0JjmZK+YGhxQzMMUYV9cPSytNCIJDwFJRrgSHp/i6CN43H/ZLhJv 9pKgVjaz4CUeDq2lX4ur5iUwwpE9iyb9ZrpF7hHq1rfiTC85Ti9dovl+NjPCUz+I5VzJabxI0+8 JnLjFbAKNx6J4fz8keut0li9UuG5N3a+cr0iyIj1fppd4tbzZlI4rZz/2qIPRc5Cmf0gCWedvDR t6MuHg0FrQpBpmYGvVRrzZ1QzOU0fG1npKtoqhB30U+/409031pdvHCEO/829Nb77FhzI7En7/9 dtl8sraV4r6j4oIRYVxv4d5d5GqpoOLQZ6osceymVRWYdntAwXysusCbXz4bQZI7n1MPhexFhdq U8DO2ScaquQ2RoFwJqLn5LQZFobbPt9jFHPgZZzgS1hZGtbySEqDAsXfCy4ijUiMzg5tkGiRBon MKYIyCwnqESV54q3MFLAxNoGOeIlExe41xNDWAV19Ga X-Received: by 2002:a05:693c:2288:b0:304:df8b:71ee with SMTP id 5a478bee46e88-3077af31664mr5621039eec.7.1780799372257; Sat, 06 Jun 2026 19:29:32 -0700 (PDT) Received: from com-75606.node.ndb.openai.org ([104.241.0.233]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-3074db560d7sm17690506eec.5.2026.06.06.19.29.31 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Sat, 06 Jun 2026 19:29:32 -0700 (PDT) From: Kyle Zeng To: netdev@vger.kernel.org Cc: uniyuki Iwashima , Kyle Zeng Subject: [PATCH net] net: guard timestamp cmsgs to real error queue skbs Date: Sat, 6 Jun 2026 19:18:19 -0700 Message-ID: <20260607021819.49698-1-kylebot@openai.com> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit skb_is_err_queue() treats PACKET_OUTGOING as the sole marker for an skb from sk_error_queue. That assumption is not true for AF_PACKET sockets: outgoing packet taps are also delivered to packet sockets with skb->pkt_type == PACKET_OUTGOING, but their skb->cb is owned by AF_PACKET instead of struct sock_exterr_skb. If such an skb is received with timestamping enabled, the generic timestamp cmsg path can read AF_PACKET control-buffer state as sock_exterr_skb::opt_stats. With SO_RXQ_OVFL enabled, the packet drop counter overlaps opt_stats. An odd drop count makes the path emit SCM_TIMESTAMPING_OPT_STATS with skb->len and skb->data. For non-linear skbs this copies past the linear head and can trigger hardened usercopy or disclose adjacent heap contents. Keep skb_is_err_queue() local to net/socket.c, but make it verify that the PACKET_OUTGOING marker is paired with the sock_rmem_free destructor installed by sock_queue_err_skb(). AF_PACKET receive skbs use normal receive ownership and no longer pass as error-queue skbs, while legitimate sk_error_queue entries keep the PACKET_OUTGOING marker and sock_rmem_free ownership. Fixes: 8605330aac5a ("tcp: fix SCM_TIMESTAMPING_OPT_STATS for normal skbs") Signed-off-by: Kyle Zeng --- include/net/sock.h | 1 + net/core/skbuff.c | 6 +++--- net/socket.c | 11 ++++++----- 3 files changed, 10 insertions(+), 8 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index dccd3738c368..95e157eee8d9 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1856,6 +1856,7 @@ struct sk_buff *sock_omalloc(struct sock *sk, unsigned long size, gfp_t priority); void skb_orphan_partial(struct sk_buff *skb); void sock_rfree(struct sk_buff *skb); +void sock_rmem_free(struct sk_buff *skb); void sock_efree(struct sk_buff *skb); #ifdef CONFIG_INET void sock_edemux(struct sk_buff *skb); diff --git a/net/core/skbuff.c b/net/core/skbuff.c index c02f0a507ba8..8eab8eb5006a 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -5450,7 +5450,7 @@ int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer) } EXPORT_SYMBOL_GPL(skb_cow_data); -static void sock_rmem_free(struct sk_buff *skb) +void sock_rmem_free(struct sk_buff *skb) { struct sock *sk = skb->sk; @@ -5459,8 +5459,8 @@ static void sock_rmem_free(struct sk_buff *skb) static void skb_set_err_queue(struct sk_buff *skb) { - /* pkt_type of skbs received on local sockets is never PACKET_OUTGOING. - * So, it is safe to (mis)use it to mark skbs on the error queue. + /* The error-queue test in skb_is_err_queue() matches this marker + * with the sock_rmem_free destructor installed by sock_queue_err_skb(). */ skb->pkt_type = PACKET_OUTGOING; BUILD_BUG_ON(PACKET_OUTGOING == 0); diff --git a/net/socket.c b/net/socket.c index 22a412fdec07..c2698a1441a7 100644 --- a/net/socket.c +++ b/net/socket.c @@ -852,12 +852,13 @@ EXPORT_SYMBOL(kernel_sendmsg); static bool skb_is_err_queue(const struct sk_buff *skb) { - /* pkt_type of skbs enqueued on the error queue are set to - * PACKET_OUTGOING in skb_set_err_queue(). This is only safe to do - * in recvmsg, since skbs received on a local socket will never - * have a pkt_type of PACKET_OUTGOING. + /* Error-queue skbs are marked as PACKET_OUTGOING in + * skb_set_err_queue() and use the destructor installed by + * sock_queue_err_skb(). PACKET_OUTGOING alone is not unique: + * AF_PACKET outgoing taps use the same pkt_type. */ - return skb->pkt_type == PACKET_OUTGOING; + return skb->pkt_type == PACKET_OUTGOING && + skb->destructor == sock_rmem_free; } /* On transmit, software and hardware timestamps are returned independently. -- 2.43.0