From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailgw01.mediatek.com (unknown [60.244.123.138]) (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 C7FAD3BB681; Fri, 26 Jun 2026 08:45:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=60.244.123.138 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782463507; cv=none; b=E4d7jTBm5ULWIPL6ew6d9x8du+4OH0hoXwkASmIR/iht79QOJAAO6jKZ0HwbljHF6arG9hJroMoNBRxXw7q//azgE11dopK6v8ahgSVS3zR/XtMWe8L7bC7pI3v5Dc25x0dVwD/NX8t/Yhtrs1EzZgpVgJpQGRX67JVtJXSgFMo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782463507; c=relaxed/simple; bh=P57UOKGR/1lJD0mKrus+RBayRSBuNY+kcCm/0HVEVrE=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=WZNa8OjbW+EMTIobDUOEEyTf+DlqoheAEyVnvG7ol/1P0mjsfNo5ghtp/uYtuabqJ3AI9Tx1jyN46Kuyo7wgkSRweuTXRLcyMeNklSLPELyfwtQL/+3taxSJ/tkv0hk+p5NHR6GPfYTxiFbcorZyiMPWpSjEIl8sf1U2khRC7CU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=mediatek.com; spf=pass smtp.mailfrom=mediatek.com; dkim=pass (1024-bit key) header.d=mediatek.com header.i=@mediatek.com header.b=jb4N5yDH; arc=none smtp.client-ip=60.244.123.138 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=mediatek.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mediatek.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=mediatek.com header.i=@mediatek.com header.b="jb4N5yDH" X-UUID: 4f433af2713b11f1b1788b6acf885367-20260626 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Type:Content-Transfer-Encoding:MIME-Version:Message-ID:Date:Subject:CC:To:From; bh=oZxFRT7y6QOtHKSYQsbCKdm/g4+aQqG38KozlNl6MJs=; b=jb4N5yDH8kKRQ/fT8Q8bAtWHSXziRWBcw2UXyDZelqD7wtq1OPVpwz/ZmQcvmFmYtDyUnDPXMVIvg7jRPqQkl4rfmlRbJeHegqDAq3KQgtvwGiiliRB2gwFCTfnSDSyqUdEi2yWWDZs2/caN6zpxQs4+WDuSsQNFVe0rvCBUF+w=; X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.3.17,REQID:20a78760-6d8c-49b8-a904-b07db37cc47d,IP:0,U RL:0,TC:0,Content:0,EDM:0,RT:0,SF:0,FILE:0,BULK:0,RULE:Release_Ham,ACTION: release,TS:0 X-CID-META: VersionHash:d497b38,CLOUDID:99bf23ee-45e6-4692-a476-3f71842ee83b,B ulkID:nil,BulkQuantity:0,SF:102|836|865|888|898,TC:-5,Content:0|15|50,EDM: -3,IP:nil,URL:0,File:130,RT:0,Bulk:nil,QS:nil,BEC:-1,COL:0,OSI:0,OSA:0,AV: 0,LES:1,SPR:NO,DKR:0,DKP:0,BRR:0,BRE:0,ARC:0 X-CID-BVR: 2,SSN|SDN X-CID-BAS: 2,SSN|SDN,0,_ X-CID-FACTOR: TF_CID_SPAM_SNR X-CID-RHF: D41D8CD98F00B204E9800998ECF8427E X-UUID: 4f433af2713b11f1b1788b6acf885367-20260626 Received: from mtkmbs11n2.mediatek.inc [(172.21.101.187)] by mailgw01.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 319282522; Fri, 26 Jun 2026 16:44:57 +0800 Received: from mtkmbs11n2.mediatek.inc (172.21.101.187) by mtkmbs13n1.mediatek.inc (172.21.101.193) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.29; Fri, 26 Jun 2026 16:44:56 +0800 Received: from mbjsdccf07.gcn.mediatek.inc (10.15.20.246) by mtkmbs11n2.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.2562.29 via Frontend Transport; Fri, 26 Jun 2026 16:44:54 +0800 From: Shiming Cheng To: , , , , , , , , , , , , CC: , , Shiming Cheng Subject: [PATCH v2] Subject: [PATCH] net: gro: fix double aggregation of flush-marked skbs Date: Fri, 26 Jun 2026 16:44:51 +0800 Message-ID: <20260626084451.27699-1-shiming.cheng@mediatek.com> X-Mailer: git-send-email 2.45.2 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-MTK: N The new skb_gro_receive_list() function is missing a critical safety check present in the legacy skb_gro_receive() path. Specifically, it does not validate NAPI_GRO_CB(skb)->flush before allowing packet aggregation. This allows already-GRO'd packets with existing frag_list to be re-aggregated into a new GRO session, corrupting the frag_list chain structure. When skb_segment() attempts to unpack these malformed packets, it encounters invalid state and triggers a kernel panic. Scenario (Tethering/Device forwarding): 1. Driver: Generated aggregated packet P1 via LRO with frag_list 2. Dev A: Receives aggregated fraglist packet and flush flag set 3. Dev A: Re-enters GRO, skb_gro_receive_list() is called 4. Missing flush check allows re-aggregation despite flush flag 5. Frag_list chain becomes corrupted (loops or dangling refs) 6. Dev B: TX path calls skb_segment(), crashes on corrupted frag_list Root cause in skb_segment(): The check at line ~4891: if (hsize <= 0 && i >= nfrags && skb_headlen(list_skb) && (skb_headlen(list_skb) == len || sg)) { When frag_list is corrupted by double aggregation, when list_skb is a NULL pointer from skb->next, skb_headlen(list_skb) dereference NULL/corrupted pointers occurs. Call Trace: skb_headlen(NULL skb) skb_segment tcp_gso_segment tcp4_gso_segment inet_gso_segment skb_mac_gso_segment __skb_gso_segment skb_gso_segment validate_xmit_skb validate_xmit_skb_list sch_direct_xmit qdisc_restart __qdisc_run qdisc_run net_tx_action Fix: Add NAPI_GRO_CB(skb)->flush validation to the early-return check in skb_gro_receive_list(), matching the defensive programming pattern of skb_gro_receive(). Fixes: 9dc2c3cd6c11 ("net: add fraglist GRO/GSO support") Cc: stable@vger.kernel.org Signed-off-by: Shiming Cheng --- net/core/gro.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/core/gro.c b/net/core/gro.c index 35f2f708f010..076247c1e662 100644 --- a/net/core/gro.c +++ b/net/core/gro.c @@ -229,7 +229,8 @@ int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb) int skb_gro_receive_list(struct sk_buff *p, struct sk_buff *skb) { - if (unlikely(p->len + skb->len >= 65536)) + if (unlikely(p->len + skb->len >= 65536 || + NAPI_GRO_CB(skb)->flush)) return -E2BIG; if (!pskb_may_pull(skb, skb_gro_offset(skb))) { -- 2.45.2