From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 8FC6B39184F; Fri, 9 Oct 2026 14:16:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791555374; cv=none; b=HgruiEHwxAPeKUAaKtueOI/6g+zIBDXApuA5js9iMWBJw5EYvh4I2tx0tP6t2ixlI7HMyCcx1iBXfv9+uxHTBYHH77g+kv84nSclOmzDuki8fwKcNKNlT+Z8jfHn889HsasySeRmXUsyLbgac5DUCsVGGJjfiKUInSUu+ifAdQA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791555374; c=relaxed/simple; bh=gNG4XHiY9XbVJ3rrxFTGVHNU7NztQLzv/7ELkEi3ek4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=vAkD7kVD9aysPadPBC8678D9qEoB/Jyrof9lcFkcC1YEx2vjv5tcGNEQE0QWA20NP7DRLXJIBx2Xoi0dy8xi+m3ktWe7C8uFJHRNVWEbuju2BqH6PivGnur2wTtQR8cmv2MGucWhLbpStkhX0sWd9zipDNirwqLA7i+izT2zS2Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=1WzwEJ9+; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="1WzwEJ9+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EB8241F000FF; Fri, 9 Oct 2026 14:16:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1791555370; bh=WmiWbihq6lLbblnmZve3zSZ/XiU89Las2ojnw4oAXhk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=1WzwEJ9+Vy2WDi5jf+fkY10eL6tJPhpWMwNF+LV3cuaQsvJSsCIwH9qnacbUC2N/l IW9kGM/AC5zEp/EBaZxoGIMr6N8yoq+ukQpM8G+zWC891xNDJHQi6zYTL27H8XPFsR NsWt7AuVeQPip7zJHjCdzQxLZeWqIcJ8xenPjUDU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?Ilkka=20Lappetel=C3=A4inen?= , Willem de Bruijn , Jakub Kicinski Subject: [PATCH 6.18 035/403] net/packet: prevent TX_RING byte count overflow Date: Fri, 9 Oct 2026 16:06:36 +0200 Message-ID: <20261009140952.932183371@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261009140952.119038291@linuxfoundation.org> References: <20261009140952.119038291@linuxfoundation.org> User-Agent: quilt/0.69 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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ilkka Lappeteläinen commit 2cf81fc9505b148b1b70068303ea6ea4b1212403 upstream. tpacket_snd() drains every SEND_REQUEST frame in a TX ring and adds each valid packet length to the signed int len_sum. Userspace can recycle completed frames concurrently, so a single blocking send call is not bounded by the ring size. After enough successful transmissions len_sum wraps into the negative range. In particular, 65536 65535-byte frames followed by a 65007-byte frame produce 0xfffffdef, or -EIOCBQUEUED. sock_sendmsg_nosec() treats that as an impossible return and triggers a BUG. On systems configured to panic on oops, a CAP_NET_RAW holder can panic the host kernel. Stop before the next frame would make the byte count exceed INT_MAX. The positive short count leaves that frame pending for a later send call. A two-thread TPACKET_V2 reproducer triggered the BUG on an arm64 build of Linux 7.3-rc4. With this change, the same reproducer returned the expected positive short count without an oops. Fixes: 69e3c75f4d54 ("net: TX_RING and packet mmap") Cc: stable@vger.kernel.org Signed-off-by: Ilkka Lappeteläinen Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20260925124829.6595-1-ilkka.lappetelainen@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/packet/af_packet.c | 3 +++ 1 file changed, 3 insertions(+) --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2873,6 +2873,9 @@ static int tpacket_snd(struct packet_soc vnet_hdr.hdr_len); has_vnet_hdr = true; } + /* Prevent the byte count from wrapping into a negative errno */ + if (unlikely(tp_len > INT_MAX - len_sum)) + break; copylen = max_t(int, copylen, hard_header_len); skb = sock_alloc_send_skb(&po->sk, hlen + tlen + sizeof(struct sockaddr_ll) +