From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 0FD781386DA for ; Thu, 4 Dec 2025 10:26:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764844022; cv=none; b=AY6DkO9j5xwz1TNaQvvzj20zSkKAkRDxa3B8FIwmdhpdB46ErwZpgujfzgwGGAAtb9B7GKjCgGkKC2VdJIMc+DFwmgGhaABUNPVqBqBWJEwcw4S9RYHmjwvNvtnm8J9v1SyN9v9EF2rsPwD6Kx79N0tVX3C8W+DROaQ3HTM56h8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764844022; c=relaxed/simple; bh=GDj0XOYw2INWgHhiZR3umk9UDMv5NvYwCIBslnkmAUE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=InF1VqI6HOckovgyXu4PakkMP2rZBgltHmMNFB6axXODyvUzpx7lEmsaGOz+Vle6/s/S60pBtlfZ322yuVHHmyAIyGzQ3D6XxXYZwaQUvyYqz/28mWB0NnmBzua5XTyFNrX/pUk/8TlvDTE80TrBRToacj74nj2xRdJZBB1oltQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=dmZxdkxh; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=Y1YwhcYH; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="dmZxdkxh"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="Y1YwhcYH" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1764844018; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=uvAgSuUIrE6mvYqIUbctn9fgbUe7c3R89eVWBs+ABmI=; b=dmZxdkxhao0pfOpUJ6mID+8QiWKhZrbA3ab3stx/wNka5FR5AxMkIggVia7rZXd7yfTllM FvanOy3ntjPRcT8NBGzHKZZIPt4VKPGDXiqX0P46OsE8rSDVR7xl+QeOrP66/+T2I183EU 7r6F/Tcb2hqGT9AX+2JtD39MbwXsBrc= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-425-v7S1np9GNtWXm5RggBcZ1A-1; Thu, 04 Dec 2025 05:26:57 -0500 X-MC-Unique: v7S1np9GNtWXm5RggBcZ1A-1 X-Mimecast-MFC-AGG-ID: v7S1np9GNtWXm5RggBcZ1A_1764844016 Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-477a1e2b372so5888895e9.2 for ; Thu, 04 Dec 2025 02:26:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1764844016; x=1765448816; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=uvAgSuUIrE6mvYqIUbctn9fgbUe7c3R89eVWBs+ABmI=; b=Y1YwhcYH3R2t7cHwbILSQMB3GkYdgotM9jU+0WRwmsf3w9iPieJv43FWos1jTUaRtT cbD8i2/EG9SJZelbGNZ25CqF2SUwJVHZO8NIC3TNJN3LUarErsAjWAgLf5Ld/SfWjg5o rf7sv5yTtrhLtgZpk0gU73E7T+eLWEmXVCib0VZpRLsM2/mNwr9GnjL40s8yiZRkxZd7 oW112HjZ2QHkDy5QWv5OE30MfHYvWnbg0yDn/1c8FMbkdC0E0Tc53az7tJaEMA6ISXru FgM6qhNygeg6nU5Fj+uD2b7Zq0nsYOlz/oi5+sHLx+bNEUAdEWSXMgmYkSMWoSQXAL6p dNWg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1764844016; x=1765448816; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=uvAgSuUIrE6mvYqIUbctn9fgbUe7c3R89eVWBs+ABmI=; b=btpa2wlg9ORGqApq3lINUiva8i0f28ruIAsvL5+luxdKUOjTLZ8jISZwxnQcU3tVQ+ dRDYrdMm2zJ6g7P6+sjr7Ioglp2CHgudzKsxuUEQSQWJbmCeNHoDSsPOFIgZ5DdFkKaN qg+9Z5Lg5NByOdlEQXULQOJIzWjnInp6ZkTqcvVrliRtPD8BAaSUBmtkM6wwKCqYjCAS X4GYilEslr4U2bsIdpg/HtQv2+/cJsQi7ERfCUQMG8JW8kOa4rbAwFeRd8YbDTH8E78u c15tNgiCCRdHvhDC18AofcAM5a0b8nacLs2IzRxIgzzu3QKlbacK3Feu5vu/H9fmvycE Fa2w== X-Forwarded-Encrypted: i=1; AJvYcCU5nDvl/rcVC0QfnN5T+YM65flE5bvmTLCJi3/0GpwmEzGj7o/3ikP/AGcpJ+fXfxWfQ1BpBpWLwUCClk0=@vger.kernel.org X-Gm-Message-State: AOJu0Yw5dDQZSll7xTk4WoFisQmex5mYBH4L7Yt/zWPNssQxyz2ThDsj Aczzhgjzla7WB5ouUNSdkf44J3WipGfQl5MHNq+C28FZ59S6nzPWXcjeS8ioRdlccnRABXKPdC9 YeQACLY6ZXmi57tH2WijCQ+0N+/9hT8xafOljhswBxv0bWsz1v23f9Qv6BqtyW90TPqATCEJDNA == X-Gm-Gg: ASbGncuYGm4rm9WFLpKuu9xnGkUKvXu0LVcPVikIqVFnjrmyuejdgvoMcHZXpQ/XAov kemDCBhTMkMxK/ngS2Hg/0tNRODoAra4UoyMGQtebFKcD1VUujHecQlNavQBS7Qavsi2xAJqUgy rOxu8bHM9k4Uiip8UGmPLEtbdgJvzewO9947sPe58RjlLLv10x4P5IybzhqrnQORiakucUyEoXW WT3TucZqrUiNcqj4NOznBR93oFYToMhOo5l4+mgt535lFDGfcG9CyFr2xFTgtCKLMi2bkmAiIN0 S65kfeGC2BZdoo+4Q/o622M8srvN8QfCeHCuZWcA2GAOgq5qdlt5ZTa1RjErKSYTwXq6jk1UumN gCoiaT2q2i1bZ X-Received: by 2002:a05:600c:1393:b0:477:7a87:48d1 with SMTP id 5b1f17b1804b1-4792af43957mr54762215e9.30.1764844016131; Thu, 04 Dec 2025 02:26:56 -0800 (PST) X-Google-Smtp-Source: AGHT+IFe2VYdkOW4g2chRFIty06a+I10kiBp0/8HHsTFNbQNcY2Gfnm64HqRkjy1wllbisNEXQJWeg== X-Received: by 2002:a05:600c:1393:b0:477:7a87:48d1 with SMTP id 5b1f17b1804b1-4792af43957mr54761915e9.30.1764844015694; Thu, 04 Dec 2025 02:26:55 -0800 (PST) Received: from [192.168.88.32] ([212.105.153.24]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47930f286f4sm23316675e9.0.2025.12.04.02.26.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 04 Dec 2025 02:26:55 -0800 (PST) Message-ID: Date: Thu, 4 Dec 2025 11:26:53 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] net: atm: targetless need more input msg To: Edward Adam Davis , syzbot+5dd615f890ddada54057@syzkaller.appspotmail.com Cc: davem@davemloft.net, edumazet@google.com, horms@kernel.org, kuba@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com References: <69298e9d.a70a0220.d98e3.013a.GAE@google.com> Content-Language: en-US From: Paolo Abeni In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/28/25 4:56 PM, Edward Adam Davis wrote: > syzbot found an uninitialized targetless variable. The user-provided > data was only 28 bytes long, but initializing targetless requires at > least 44 bytes. This discrepancy ultimately led to the uninitialized > variable access issue reported by syzbot [1]. > > Adding a message length check to the arp update process eliminates > the uninitialized issue in [1]. > > [1] > BUG: KMSAN: uninit-value in lec_arp_update net/atm/lec.c:1845 [inline] > lec_arp_update net/atm/lec.c:1845 [inline] > lec_atm_send+0x2b02/0x55b0 net/atm/lec.c:385 > vcc_sendmsg+0x1052/0x1190 net/atm/common.c:650 > > Reported-by: syzbot+5dd615f890ddada54057@syzkaller.appspotmail.com > Signed-off-by: Edward Adam Davis This needs a suitable fixes tag, and you should specify the target tree into the subj prefix, see: https://elixir.bootlin.com/linux/v6.18/source/Documentation/process/maintainer-netdev.rst#L61 > --- > net/atm/lec.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/net/atm/lec.c b/net/atm/lec.c > index afb8d3eb2185..178132b2771a 100644 > --- a/net/atm/lec.c > +++ b/net/atm/lec.c > @@ -382,6 +382,15 @@ static int lec_atm_send(struct atm_vcc *vcc, struct sk_buff *skb) > break; > fallthrough; > case l_arp_update: > + { > + int need_size = offsetofend(struct atmlec_msg, > + content.normal.targetless_le_arp); > + if (skb->len < need_size) { > + pr_info("Input msg size too small, need %d got %u\n", > + need_size, skb->len); > + dev_kfree_skb(skb); > + return -EINVAL; > + } Can this be reached by pppoatm_send? Are you sure that the data will always be available in the linear part? /P