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 E63574EFFD4; Tue, 13 Oct 2026 11:46:31 +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=1791891993; cv=none; b=K+l0dKMiAx3FXSKjw9pnjFBTRVHJaDJhs/Gh7k7kbXcWd4JZ8FhQ0KWnV6Rh0JldrACyicN4EPTAwWOCdlXRdWc/xc2rIi/hvedyTnSr7Dt0rShHFqA8H4e0vMhsXH3YHTHzJM4353JJ8TpGyO/P+awKNV+cUspUyJMqHiVNV6w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791891993; c=relaxed/simple; bh=Yw2V0W6TLIT247I8TdxAz+6tLQgF5uGGHsHjVbGQYpU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BF+5scaI79rb5uwdRIXHD7o2fyGAyno2Ud/GAQZbxAsCOZ8NaIQazCQK4rbu7CVMb7V7IJ0shzXrGCkH+3pH00CIiOipcM1tG6V1L8LehlGjPTdrSnA8tkbLV7+H0jESLaXsBu1KpgyoLm88SDfP0OscRYTVnm0p88sxPcS1wc8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=mOOaO2UL; 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="mOOaO2UL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E848D1F00893; Tue, 13 Oct 2026 11:46:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1791891991; bh=mVJmHMC0MJK9FPfV6jWkkaGDERKNK43ujazL/k/oiug=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=mOOaO2ULfY68GZQoZokEHduhGvitXnlY4A5m5YkqNWuIRXlqjfyK8zkvXlY32KcJq H0h54SAXKMAMHrBw+iorORXeuvgqrspJNG56IXKGjrSBtyj4UbLA0UsY7+w5HoYX7+ FNlinttKRLF+yzlYPNCSuCmnaxhDcw/2MGFRiZ5M= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Oliver Hartkopp , zjamg , Quchaosheng , Shaunak Datar , Marc Kleine-Budde Subject: [PATCH 7.2 024/281] can: dev: init_can_skb(): restore skb header initialization Date: Tue, 13 Oct 2026 13:35:40 +0200 Message-ID: <20261013112855.637289124@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261013112855.045212108@linuxfoundation.org> References: <20261013112855.045212108@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-Transfer-Encoding: 8bit 7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: zjamg commit 0a04c0cb8606ff88399489d03ef255afe90d0d5f upstream. Commit 9f10374bb024 ("can: remove private CAN skb headroom infrastructure") removed the skb_reset_mac_header()/skb_reset_network_header()/ skb_reset_transport_header() calls from init_can_skb(). As a result, RX skbs from alloc_can_skb() and friends again carry mac_header = 0xFFFF. When such an skb reaches packet_rcv_spkt() (SOCK_PACKET), the push length calculation overflows and triggers skb_under_panic -> kernel BUG -> full machine panic. The same issue was originally reported in 2014 on linux-can and fixed by commit 969439016d2c ("can: add missing initialisations in CAN related skbuffs"). packet_rcv_spkt() itself has never been hardened: only packet_rcv() and tpacket_rcv() gained dev_has_header() checks in commit d549699048b4 ("net/packet: fix packet receive on L3 devices without visible hard header"). Fixes: 9f10374bb024 ("can: remove private CAN skb headroom infrastructure") Cc: stable@vger.kernel.org Reviewed-by: Oliver Hartkopp Acked-by: Oliver Hartkopp Signed-off-by: zjamg Tested-by: Quchaosheng Link: https://patch.msgid.link/20260917123716.63116-1-ndaugoing@gmail.com Reported-by: Shaunak Datar Closes: https://lore.kernel.org/all/20260918151606.765490-1-shaunakkdatar@gmail.com Signed-off-by: Marc Kleine-Budde Signed-off-by: Greg Kroah-Hartman --- drivers/net/can/dev/skb.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/drivers/net/can/dev/skb.c +++ b/drivers/net/can/dev/skb.c @@ -210,6 +210,10 @@ static void init_can_skb(struct sk_buff { skb->pkt_type = PACKET_BROADCAST; skb->ip_summed = CHECKSUM_UNNECESSARY; + + skb_reset_mac_header(skb); + skb_reset_network_header(skb); + skb_reset_transport_header(skb); } struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf)