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=1794531941; b=BrCCq5q2UoyKBt666xTs6YHaUogqHds+gSc6ibAueJBMbrrVOd+LhzR2TyZIX7iw/7/Z 3oTV7f/BMU752+OJy2Nxv0cBmkCrvWHwUOenw3g84p0HEPzMGdLlPrkpPRhUEpZDpj36Y TWx5L0E+0pn4lx3+RVglZuxvTYsnXlWrHh0Kn064Rmzsea4hMScMmm/O1kbbhsDhrO/KF Og/5zltYBeYyjDmXIipSSGjAtp3y00IJm6aX0e3R+lX/rPDA4Hl99it7XYTJgiFMYMoIl IYuasKNH0dF+cujyOOM9vdX3GDBEarRT9djLn6goq//gEDxosaXz/GWfuLuLozSNepg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794531941; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=3onjlPE0aNtWXkAETxOWtjeOcUxVDxYLzutBFrCt8ow=; b=RhZsX2UNlREQf7BW7JcKDr8NBveZXAVQOrb6HfgPBsQD5BR4Nnp8BikfFdiirQ7OEQCa Gy5ok8VvsBPurIiKktAVURtVYcUf0IXE5PjqdKAeRQz+1GvRWYbqrWj5KttRAuIGUKBSy WA7IoQZfBgMyngFNZASaB2kprfZAVzR8VKe8FVtgTDqg2aJYqegx6JxaDs/QFpmielqob ji3iDY2BaRH1y8d2xlFF5JHb+7VQg+7siP+ZhP7fWK5hivstuCjpk8TbxZd33UHNHPbJ0 hqsoEzvgldFO+cCjRxpcF1y2cwe1SjTzw1+VTj+0CJCucJCp86OuRiO05xdBUg3JcTg== 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=ml9t7XeJ; 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 AE2EE606A323 for ; Fri, 13 Nov 2026 01:05:41 +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=ml9t7XeJ Received: by smtp.kernel.org (Postfix) with ESMTPSA id CCEBD1F000C6; Fri, 13 Nov 2026 01:05:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794531941; bh=3onjlPE0aNtWXkAETxOWtjeOcUxVDxYLzutBFrCt8ow=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ml9t7XeJHWo2fQwJM9b+jiOkb9R2oVijhEmUAxmzEYsYUrGuGTevUgyOB/ii1OMkR 6Ho3Q4jgvK7ouUHd+XKluLin6ItmPLJHLbhQ2UogdFI34T9R5S+ay/Ku2Uo7ypqi0H oWTTGw7ytYbd+11ib6kEqN26x3QB/EpjhcHqd0lU4Ga+t0CF6Qf+vA6LLqTkchxLf8 8Np7Zmk1RUgUGMtlCYztUukWb37whxtkNwMgrOvLQEZKulN6prNDLKoIjGZ3Pr2O3/ GvPQlaUA0jbihAzO5+GHOw7Jbsnq9aSfSom8to/60j2JCBiqd04QcxgCorUpzoaXIs DaVq9gPxdRySQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Vincent Mailhol , stable@kernel.org, Marc Kleine-Budde , Sasha Levin Subject: [PATCH 6.6.y] can: dev: can_dropped_invalid_skb: drop CAN XL frames on non-CAN XL devices Date: Thu, 12 Nov 2026 20:05:39 -0500 Message-ID: <20261113010504.443628-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261109201311-failed-6.6-0fce44e29fce@kernel.org> References: <20261109201311-failed-6.6-0fce44e29fce@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 unavailable can_cap_enabled(dev, CAN_CAP_XL) 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