From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794532872; b=Z4Cn3o6nTOWaFQEhrI3EEGGg+C9s+Al3SrtZqPFII/Y7C8JZpxyyE7Speg6d0Wh/R53/ wzdyibb1TOgrPwoUB7gE8hU/VCktSm9zsDUlNEh3iNRMy48xuc73aWRbUFbi5ci/I+joZ Rb7GNO2fefQ0o34NFRyckjDdu2QB4PAPPMp6p2+6ri4IeTF37Ng777OBJGfgOvDm12NHk onSF7jYXHCAlCw+VSYMostaD8jeBjIimYX87vwa2Nkwfxgl3px3wDpWjiKhWbmHREB3RP NfdebQSgVwCE3uJcXAoJaubgSu5a74RoRb6V8hKtPVv39zTYLYKIfEadd55BPw5nPoQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794532872; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=n+9U+PhY1PLOfrLchkOXikugpha6tXqTgqlNCna860o=; b=pzJRyFwjrmWFALgRz0x4o+CxWpvE+ymDMDo/Xp4uIiUg2FIFDCEh3T1puyy4HLpeTfih rE2fNow6UwkUrGm6K2y7X1mfyQr3MAfti92WPq8IOUqsiEtO67MfIoXDYLkGLn97T5G8c PFHOt8Ihh4s64AjuAkuw+rYQcwo3TH+mSKM/jfN8t/aDrX2Ktp+P4DswumMntbr8jiBKl 5k38gzjlPZZEmZaXlz5LGicWQdDorBCxH4BIiLQpjANhRGZZSKA8i4vNq/ncPdy2syHah iak3iydw4MWvZ/WdLRgzAWYQ8XM8fMJOpHCn2Gf8czzsVtP/5OiEon4RG7o1zzRBEnA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=fsLLlTpt; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AFAC9606A327 for ; Fri, 13 Nov 2026 01:21:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=fsLLlTpt Received: by smtp.kernel.org (Postfix) with ESMTPSA id B00791F000C4; Fri, 13 Nov 2026 01:21:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794532872; bh=n+9U+PhY1PLOfrLchkOXikugpha6tXqTgqlNCna860o=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=fsLLlTptZPIWtahYBlaOht7RfydC7iWdfeXhLteUgLLCeW0kTd192aORDdIATRPLk /meiuMYAkgZvP5b38uTCFMc8Zu+OcX2bXfq9zOj3cNrCQJ5scRyyx7xP8wUFML/ClZ 5g7EBolLXXtuabVKWOu0cfGGH0AgPWHn7UGF/yIPb8W1DVAbLkLx7XQ/pVX4Rr38aC +CMvRAvu6+Fnz39yTZJjSum+FN2BZsg/32sAV9x95gQhk1Hh4sTpvj8lGP379zA9mS JsWzHX9pKG4WStqMz9as37Y5piGlUn1YziiISjrXT0lPL6QPmnzkYvN8xiWtjdoZ/2 MhUfLO/HdBXSg== From: Sasha Levin To: stable@vger.kernel.org Cc: Vincent Mailhol , stable@kernel.org, Marc Kleine-Budde , Sasha Levin Subject: [PATCH 6.1.y] can: dev: can_dropped_invalid_skb: drop CAN XL frames on non-CAN XL devices Date: Thu, 12 Nov 2026 20:21:10 -0500 Message-ID: <20261113012045.553488-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261109201806-failed-6.1-0fce44e29fce@kernel.org> References: <20261109201806-failed-6.1-0fce44e29fce@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Vincent Mailhol [ Upstream commit 0fce44e29fce4b07642491b098afb41bd571e4f2 ] Sending a PF_PACKET bypasses the CAN framework logic and can directly reach a CAN driver's xmit() function. The PF_PACKET framework only checks that skb->len does not exceed the net_device MTU. For a CAN device that is not CAN XL capable, anything above CANFD_MTU (72 bytes) is therefore dropped before it reaches the driver. However, CAN XL frames are variable length. can_is_canxl_skb() accepts lengths in the range CANXL_HDR_SIZE + CANXL_MIN_DLEN up to CANXL_MTU, i.e. 13 to 2060 bytes. As a result, an ETH_P_CANXL skb with a length between 13 and 72 bytes can pass both the MTU and the can_dropped_invalid_skb() checks. A driver that does not support CAN XL will interpret canxl_frame->flags as a length because of the overlap with can_frame->len. And because CANXL_XLF is set, the resulting length is between 128 and 255. For drivers that do not check can_frame->len before copying can_frame->data, as most drivers do, this results in a buffer overflow of up to 247 bytes. Drop ETH_P_CANXL skbs if the device does not have the CAN_CAP_XL capability. Keep can_is_canxl_skb() for the validation of CAN XL skbs. Closes: https://sashiko.dev/#/patchset/20260731-master-v5-0-5b27029dee20@qq.com?part=1 Fixes: fb08cba12b52 ("can: canxl: update CAN infrastructure for CAN XL frames") Signed-off-by: Vincent Mailhol Link: https://patch.msgid.link/20260731-drop_canxl_frames-v1-1-7387b70353b3@kernel.org Cc: stable@kernel.org Signed-off-by: Marc Kleine-Budde [ sashal: replaced the unavailable can_cap_enabled() capability check with can_is_canxl_dev_mtu(dev->mtu) ] Signed-off-by: Sasha Levin --- drivers/net/can/dev/skb.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/can/dev/skb.c b/drivers/net/can/dev/skb.c index 6fb1f9b2a9e20..4f5eec05db220 100644 --- a/drivers/net/can/dev/skb.c +++ b/drivers/net/can/dev/skb.c @@ -354,7 +354,8 @@ bool can_dropped_invalid_skb(struct net_device *dev, struct sk_buff *skb) break; case ETH_P_CANXL: - if (!can_is_canxl_skb(skb)) + if (!can_is_canxl_dev_mtu(dev->mtu) || + !can_is_canxl_skb(skb)) goto inval_skb; break; -- 2.53.0