From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 A5EEB46447 for ; Sat, 24 May 2025 15:49:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748101747; cv=none; b=bEkSuikviSArXd98L7uLVL8jhLyMBkxI3xgADhQtuyjP3HTjro2B7vLJJ1wV8qXUTtNo9Td1VoRpN+UxI/nr1cQZTpU95NOFwnXoBnsqYT8BeE/KdQfTLV0+9z0qxlk04iFIqtUhdG7x3+igyWgl57td0t6+JDHmcOekBwucVok= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748101747; c=relaxed/simple; bh=d4rnvSz2Rkp5rObA3KBrvGxixY864quFwqynMPEHvxw=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=cyp0+SVdqKvMVbUbzIuRjQjQU9KIUDjUATZAAAET9CY2DNOkRnmBqnIVy/UZAkdcF3Xf6coU3BbC7lraz4aFfxZItRvv0nJaCfKfDh+s521acRwsFn3GzfyG+0iReuv61j59+Es4cKmv2s6fQ34jKdyaAmc5XxrPB791seSHLsg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Bk9bf2rk; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Bk9bf2rk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 163DFC4CEE4; Sat, 24 May 2025 15:49:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1748101747; bh=d4rnvSz2Rkp5rObA3KBrvGxixY864quFwqynMPEHvxw=; h=Subject:To:Cc:From:Date:From; b=Bk9bf2rkzTYJMLiw2VH7nnkjiiXnpJAHOI0qYyeVK3WEIqb6+aSB68kqKMXwXg7cV OJL4ONk/7jqQXV+/9ugQ6dn8Z0OvD6bJ6nF89y2AixKg2iJI7k9LsSlMZuh64LZPzZ XMRXF5QY8Gnd17hfmr9V2H6gtSZIX1BwB283lKW4= Subject: FAILED: patch "[PATCH] net: dsa: microchip: linearize skb for tail-tagging switches" failed to apply to 5.15-stable tree To: jakobunt@gmail.com,jakob.unterwurzacher@cherry.de,kuba@kernel.org,olteanv@gmail.com Cc: From: Date: Sat, 24 May 2025 17:49:00 +0200 Message-ID: <2025052400-backpack-superior-fb22@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x ba54bce747fa9e07896c1abd9b48545f7b4b31d2 # git commit -s git send-email --to '' --in-reply-to '2025052400-backpack-superior-fb22@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From ba54bce747fa9e07896c1abd9b48545f7b4b31d2 Mon Sep 17 00:00:00 2001 From: Jakob Unterwurzacher Date: Thu, 15 May 2025 09:29:19 +0200 Subject: [PATCH] net: dsa: microchip: linearize skb for tail-tagging switches The pointer arithmentic for accessing the tail tag only works for linear skbs. For nonlinear skbs, it reads uninitialized memory inside the skb headroom, essentially randomizing the tag. I have observed it gets set to 6 most of the time. Example where ksz9477_rcv thinks that the packet from port 1 comes from port 6 (which does not exist for the ksz9896 that's in use), dropping the packet. Debug prints added by me (not included in this patch): [ 256.645337] ksz9477_rcv:323 tag0=6 [ 256.645349] skb len=47 headroom=78 headlen=0 tailroom=0 mac=(64,14) mac_len=14 net=(78,0) trans=78 shinfo(txflags=0 nr_frags=1 gso(size=0 type=0 segs=0)) csum(0x0 start=0 offset=0 ip_summed=0 complete_sw=0 valid=0 level=0) hash(0x0 sw=0 l4=0) proto=0x00f8 pkttype=1 iif=3 priority=0x0 mark=0x0 alloc_cpu=0 vlan_all=0x0 encapsulation=0 inner(proto=0x0000, mac=0, net=0, trans=0) [ 256.645377] dev name=end1 feat=0x0002e10200114bb3 [ 256.645386] skb headroom: 00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 256.645395] skb headroom: 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 256.645403] skb headroom: 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 256.645411] skb headroom: 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 256.645420] skb headroom: 00000040: ff ff ff ff ff ff 00 1c 19 f2 e2 db 08 06 [ 256.645428] skb frag: 00000000: 00 01 08 00 06 04 00 01 00 1c 19 f2 e2 db 0a 02 [ 256.645436] skb frag: 00000010: 00 83 00 00 00 00 00 00 0a 02 a0 2f 00 00 00 00 [ 256.645444] skb frag: 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 [ 256.645452] ksz_common_rcv:92 dsa_conduit_find_user returned NULL Call skb_linearize before trying to access the tag. This patch fixes ksz9477_rcv which is used by the ksz9896 I have at hand, and also applies the same fix to ksz8795_rcv which seems to have the same problem. Signed-off-by: Jakob Unterwurzacher CC: stable@vger.kernel.org Fixes: 016e43a26bab ("net: dsa: ksz: Add KSZ8795 tag code") Fixes: 8b8010fb7876 ("dsa: add support for Microchip KSZ tail tagging") Reviewed-by: Vladimir Oltean Link: https://patch.msgid.link/20250515072920.2313014-1-jakob.unterwurzacher@cherry.de Signed-off-by: Jakub Kicinski diff --git a/net/dsa/tag_ksz.c b/net/dsa/tag_ksz.c index c33d4bf17929..0b7564b53790 100644 --- a/net/dsa/tag_ksz.c +++ b/net/dsa/tag_ksz.c @@ -140,7 +140,12 @@ static struct sk_buff *ksz8795_xmit(struct sk_buff *skb, struct net_device *dev) static struct sk_buff *ksz8795_rcv(struct sk_buff *skb, struct net_device *dev) { - u8 *tag = skb_tail_pointer(skb) - KSZ_EGRESS_TAG_LEN; + u8 *tag; + + if (skb_linearize(skb)) + return NULL; + + tag = skb_tail_pointer(skb) - KSZ_EGRESS_TAG_LEN; return ksz_common_rcv(skb, dev, tag[0] & KSZ8795_TAIL_TAG_EG_PORT_M, KSZ_EGRESS_TAG_LEN); @@ -311,10 +316,16 @@ static struct sk_buff *ksz9477_xmit(struct sk_buff *skb, static struct sk_buff *ksz9477_rcv(struct sk_buff *skb, struct net_device *dev) { - /* Tag decoding */ - u8 *tag = skb_tail_pointer(skb) - KSZ_EGRESS_TAG_LEN; - unsigned int port = tag[0] & KSZ9477_TAIL_TAG_EG_PORT_M; unsigned int len = KSZ_EGRESS_TAG_LEN; + unsigned int port; + u8 *tag; + + if (skb_linearize(skb)) + return NULL; + + /* Tag decoding */ + tag = skb_tail_pointer(skb) - KSZ_EGRESS_TAG_LEN; + port = tag[0] & KSZ9477_TAIL_TAG_EG_PORT_M; /* Extra 4-bytes PTP timestamp */ if (tag[0] & KSZ9477_PTP_TAG_INDICATION) {