From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f177.google.com (mail-pl1-f177.google.com [209.85.214.177]) (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 EC69E3195F0 for ; Thu, 14 May 2026 16:51:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778777515; cv=none; b=kXb9JBA7aTDIKEd4/W0gHUvcEd/NAJ+/VTmYFlKT9vOjBWwLVfkBrVTbZ7qwojGu4j833V4bUJQhwel2LCCp4t+uskQjAiuIq5II7EZxXsxhIMJV/dnkvNv6NioV8PjqWu6mMd+Osg5KcByLsF8jaC69nS/CkyiH9n7am4gcqOI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778777515; c=relaxed/simple; bh=xaDJ6AhrGPsK6Co3K1k8EdNzGxNV+cBSK5nP6nfNhss=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=dvAQqTm+4KG+X6cNxCpGzyehphD8ifakOAI0qfhpW4CEo+c2DDKdbDHW4MuMI9awyE/prkzu4MRE/c+LyUAHCCS+xuLwYujAlA9riyhuaHe01NTFvX8uezytfIWBIwPJ9XLO52phyDe2bVMNqaEEYYPb9gJGEYy9lLq+jFvdnlA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=F4x7wlSD; arc=none smtp.client-ip=209.85.214.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="F4x7wlSD" Received: by mail-pl1-f177.google.com with SMTP id d9443c01a7336-2babfd18435so41996515ad.1 for ; Thu, 14 May 2026 09:51:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1778777513; x=1779382313; 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=BDjribekpIomxI3HWRnZ6Olveu3FkT0qRUsHGP8CKgU=; b=F4x7wlSDyeiaJvXQbAP7F9XUi0vBKz9AkN9ORWP5acaXAy/K5ftR7fZo07po4MnkjE Wi6Q6vFFm8zW1PvGFPVXD3nDkQ8TiwZ6eZ/bMlpUSRYUviyxUMr0wyqZndIHM4ToaKph ONqxwJCnXN8oqY7s4zMN1FmC+3ru68QHZRXh+wz22pAedh73nlEyZqcijivKQiqN9mTh 3KBjJKpLFMZ5YmYB4DNy8AQ8LcOvz76GyLNe3RHe6LK186fvI5A0RYs+GVVOQUrQvMSy wOuGC8MzKPkSeAWX61q5mE9632Mfj4lS8T4n/Kd3jgRb7psOtTn58dC9gZ1AFIGlv28A vlAA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1778777513; x=1779382313; 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=BDjribekpIomxI3HWRnZ6Olveu3FkT0qRUsHGP8CKgU=; b=soYvc3dIV35QRTUQO5YLki3qk2BgH4NhH3lKMs+IG4mYdpv9o/BPKiuQRip05ezYja F6as0XHoN2sCmw5EMnpxM0EbmIh6s0Yzq2IEpT6Ojayp9RnPz6zTZU0YbwxB8VXCYRgY Bm4ltndG8FWAm6k6WducXD/3cFXFbl9esdIIfsAPvZremg7Y+0oZb/B/8PPLDunvAg5G 4ml+9SeuA19EtM6rdp3sxeGfyIAzPSqo/MZWHkKtA2TcNLR0EgvINExre6BQrymIFMcD eDLWMoAKjcw7WwDoeibAu3oObTfg/XNT9wxFIY+BcIGuDm4BG4rs7HPbl3GAoWZopmDT Qb/Q== X-Forwarded-Encrypted: i=1; AFNElJ/cFUoz5DajuC5eE2KCGo0oMWz63ylZpi5RsbOiJ4oekTXZ3qqA1rJr8IzJGyozHd1z0ITS8a4=@vger.kernel.org X-Gm-Message-State: AOJu0Yw8pf1MnBVb9OyWp2NFRn6D1Qt7m3Rro8yJfMG73srcvKXbxhs/ 6y43nPIR7gvyq027MPGHEJ4nzflsJBCv6Bb23J++9uAfKVhhOmI4SdKt0Nv0Vtc9AdY= X-Gm-Gg: Acq92OFhuue6GRwBLPBJoE/xJta0WeVcz+Fo0OvvtvBEKrlJBAPDq00M72haAnkmIuq 6H8TtigVzYAW3Ug+7uFdGwK5aNyadhR80JteEmZgw2kKo1ht81jRiFAmoJ8XAt3wZhCp85AFfw0 kFCPuUJjZXfdDJjsKTazxgGWA8HIBIB5QapmOtvmzT4gMweLmGm0DU6lJ7DgdKGbhIQ5pTV/T2v GaPjYzMk70+ObDekuuBTE+QHzhV25eIr4xkswWdm5vvoM1uDqi8jKpO0r7GOSnGuYsqbs+jjzUH PoKiDBI0UY0fDqqd5NVhHuV3kL6i0QlqSRsFcJF00J1xN7xvgGzgg/IUxRQmbRONccIfGnbkVES PAhnehWowEIs/Bx2u8ue3svUfx3dqeuQ/pxvIcTbMz3Rn8rAAzm0GtQYZvNQIiBGVuWWdcVKZhV nzOWeOH/Ac5BmzvYzaZBmmIeKi5BHj3g== X-Received: by 2002:a17:903:2a87:b0:2ba:4eee:6c1e with SMTP id d9443c01a7336-2bd7e8214d5mr3623325ad.15.1778777513222; Thu, 14 May 2026 09:51:53 -0700 (PDT) Received: from Tplus.localdomain ([114.243.117.21]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2bd5c2631basm27937825ad.34.2026.05.14.09.51.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 14 May 2026 09:51:52 -0700 (PDT) From: Qi Tang To: davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, edumazet@google.com Cc: netdev@vger.kernel.org, lyutoon@gmail.com, stable@vger.kernel.org, Qi Tang , David Ahern , Ido Schimmel , Simon Horman Subject: [PATCH net 1/4] ipv4: validate ip_options length in __ip_options_echo() against skb tail Date: Fri, 15 May 2026 00:51:31 +0800 Message-ID: <20260514165139.436961-2-tpluszz77@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit __ip_options_echo() re-reads each option length byte (RR/TS/SRR/CIPSO) from skb->data when building the echoed options into a 40-byte __data[] buffer. __ip_options_compile() saved only the option offset into IPCB(skb)->opt, not the length. An nftables LOCAL_IN payload write reachable from an unprivileged user namespace can mutate the length byte between parse and recvmsg, turning a parse-time validated 7-byte option into a 255-byte read. unsigned char optbuf[sizeof(struct ip_options) + 40]; /* in __ip_options_echo: */ optlen = sptr[sopt->rr + 1]; /* re-read; nft can mutate */ memcpy(dptr, sptr + sopt->rr, optlen); /* into 40-byte buffer */ The destination is a stack buffer in ip_cmsg_recv_retopts() and a DEFINE_RAW_FLEX() buffer in icmp.c / ip_output.c sized IP_OPTIONS_DATA_FIXED_SIZE (40). KASAN reports a stack-out-of-bounds write of size 255: BUG: KASAN: stack-out-of-bounds in __ip_options_echo+0x7fc/0x1310 Write of size 255 at addr ffff88800a657950 __asan_memcpy+0x3c/0x60 __ip_options_echo+0x7fc/0x1310 ip_cmsg_recv_offset+0x58b/0xd10 udp_recvmsg+0x8da/0xc20 ____sys_recvmsg+0x1b1/0x620 Validate that each re-read option length stays within skb_tail_pointer(skb) before the memcpy. Reported-by: Qi Tang Reported-by: Tong Liu Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Qi Tang --- net/ipv4/ip_options.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/net/ipv4/ip_options.c b/net/ipv4/ip_options.c index be8815ce3ac24..1cc6096e6dd9d 100644 --- a/net/ipv4/ip_options.c +++ b/net/ipv4/ip_options.c @@ -91,6 +91,8 @@ int __ip_options_echo(struct net *net, struct ip_options *dopt, if (sopt->rr) { optlen = sptr[sopt->rr+1]; + if (sptr + sopt->rr + optlen > skb_tail_pointer(skb)) + return -EINVAL; soffset = sptr[sopt->rr+2]; dopt->rr = dopt->optlen + sizeof(struct iphdr); memcpy(dptr, sptr+sopt->rr, optlen); @@ -105,6 +107,8 @@ int __ip_options_echo(struct net *net, struct ip_options *dopt, } if (sopt->ts) { optlen = sptr[sopt->ts+1]; + if (sptr + sopt->ts + optlen > skb_tail_pointer(skb)) + return -EINVAL; soffset = sptr[sopt->ts+2]; dopt->ts = dopt->optlen + sizeof(struct iphdr); memcpy(dptr, sptr+sopt->ts, optlen); @@ -145,6 +149,8 @@ int __ip_options_echo(struct net *net, struct ip_options *dopt, __be32 faddr; optlen = start[1]; + if (start + optlen > skb_tail_pointer(skb)) + return -EINVAL; soffset = start[2]; doffset = 0; if (soffset > optlen) @@ -174,6 +180,8 @@ int __ip_options_echo(struct net *net, struct ip_options *dopt, } if (sopt->cipso) { optlen = sptr[sopt->cipso+1]; + if (sptr + sopt->cipso + optlen > skb_tail_pointer(skb)) + return -EINVAL; dopt->cipso = dopt->optlen+sizeof(struct iphdr); memcpy(dptr, sptr+sopt->cipso, optlen); dptr += optlen; -- 2.47.3