From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qt1-f173.google.com (mail-qt1-f173.google.com [209.85.160.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D8C7D3612E9 for ; Wed, 15 Apr 2026 06:37:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776235037; cv=none; b=NGGOT6plGANQ9PaBvIimQ0W/wSZYFCsti7pJBKhnFHmYkjI42iyOsgpzyNwbUdhHPRr7eAjWxatJRDDvrY3zwWjo4Z7LtHsGAHNETDI4S0Pjo0m3cd83D9Ta1gLwxtsZ4xL0jcg44pTkjzKt29wpYU6GRHcqzr3xrWbVhkAzUgo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776235037; c=relaxed/simple; bh=yJ9CzZdh0ITtrg/Qg4Whi7FTsOhB5NFwZmHZHk5gvDQ=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=UB18BbwjHz5uGqsYypynShcomo/Nt5Ypr4dtxK7P44wadWYjYcKrQ9FyIEokwtNUdMTLGNSf2zuMJAssRiCc5tAhuElqxmzXJVed7o2Mzz1yX+zZpwTsuMtEZc1kQQMgThR9IcgsFGx905tKrMS8Rf93S4bSz9Qv9s3UxYmuHuY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=LzME5p3c; arc=none smtp.client-ip=209.85.160.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="LzME5p3c" Received: by mail-qt1-f173.google.com with SMTP id d75a77b69052e-506a6cf8242so48843981cf.1 for ; Tue, 14 Apr 2026 23:37:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1776235034; x=1776839834; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=rrC9vNrM6E6rzZeBaqxVv48Wut0j5e/JM27h9uWS1lQ=; b=LzME5p3cZ//ZOSu7QCVtD6m3PnoYyPtXmpsibWdgflbxsNBCfy2GRVPZNtdXHqqI09 9wjUKpf+PObtTmjsiMfPiWuoVqIMwf/xCf3ghGfEYCmF5/4dUhH1ojyedtqPzaGptyU/ pyA3mkEhLMSfpIBlkbt7FGp3+Kejsix0vVXOKilLFDxmvBjbY46Ujf48/4d2XkoZo6fQ Fr2qiob10hzpVyUmkek0gYKDiMo/tVcEsKSlNeZYB1un9G+Rjb/g8id3kFkjZWWtP2Td z2Q1xN9aZtsTMMWHpVDYBnZ+uYfehu5FMFAyOpfEDUgPSJxBPfQTpJbFOcq19HFTI7jK o8KQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776235034; x=1776839834; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=rrC9vNrM6E6rzZeBaqxVv48Wut0j5e/JM27h9uWS1lQ=; b=ooQljqQrXPsKEHiOXmRwgZDkjQK+kJgOAzyON/8AG942gI/y98FIHgYGkKSd6/NroO X81mcsDWVwrvUwFKOyTP71rVBw4Jj7ibz8FDRqLNtekvhC6gHTtId7XTJLZCmDjVE/kh i0MDFL/j9pMhn/e41SFEhlWXQh9BYNvsVfYPh9MGm1CPJ3TiFTu3jiZ12XHRXIRsr1D5 FMPzjb2YfWPeMhyDz/WRCoYzjfXnlVRvOBCheNXUjyzM/IssU1c4ngwF5AmivGB30EVU QUngwHATStT3dL63khbA6qIHm8IQVTzVKpmynXtnzXVQzjhxBmt+736tkhm9dKqiNWPs smrw== X-Gm-Message-State: AOJu0YzNhUkOZx4wKOez9EAHLM+OlNZsW/fqMbwELdC0wOQ+qhOZ7KqD fragxmTdqUCtVkl+89EyZHRdA29d082optP81AN0+xtFeCKfXbgiuWhy X-Gm-Gg: AeBDies+4zMwAYvTjYu5K0iLziREeQpqd5oV7aoLMJbAnwrrgjCSesRSJLCRcT64LB2 uheGEpUNVxcntadVmd5M7cQ8KqDGCqunP23ImQkumZZn4nycXX6dEvEiRnc99zt40vLpGztN5Ay kIwMv4RUALUgNtNxLe/sCpcPXXgRVPmwKKjuKHvS9og54ARxctSYZ4x8R51lWt4Nx/xJjNuWKpF mZSSyNaqk8yfi9lp13/X6kJImZqHACUR5zbWSAiIaZvNjTML2cjAnj2sT2XQQSNwcAGOqGmoOYd dNy/m0yaY/nE+d683n9a9DATnYJYJZx/vswTUTNgNg3sL3pmx16NpTb8ujMjnwlhO2d2IfLG6e+ QNWRvo2dIb/SryUf+e9wpmJ79GIMiqSgOclFNqJzM53DMyeDmsP3qhTw16YwDh14XSTLciRohxK PjvGUwVCbAZIN1hK2SB1mOEcsox3OPw+W8sW3O5n/6FPfGs3dc+LDz9cc9TL/RVIFQsQFDK1+pb yhfiy33uZ6f88/Pnbe8GAJrJo6R0Cdl+03/iDo= X-Received: by 2002:a05:622a:134c:b0:50d:82ca:7c9c with SMTP id d75a77b69052e-50dd5adaf18mr314133561cf.14.1776235033794; Tue, 14 Apr 2026 23:37:13 -0700 (PDT) Received: from TDC4045031631.e0cglfehwr0e5gttmepj3hi3hf.ux.internal.cloudapp.net ([20.63.37.123]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-50e1afebd48sm6222121cf.26.2026.04.14.23.37.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Apr 2026 23:37:13 -0700 (PDT) From: Ashutosh Desai To: netdev@vger.kernel.org Cc: linux-hams@vger.kernel.org, jreuter@yaina.de, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, stable@vger.kernel.org, linux-kernel@vger.kernel.org, Ashutosh Desai Subject: [PATCH v3 net] ax25: fix OOB read after address header strip in ax25_rcv() Date: Wed, 15 Apr 2026 06:36:54 +0000 Message-Id: <20260415063654.3831353-1-ashutoshdesai993@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-hams@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit A remote station can send a crafted KISS frame that is just long enough to pass ax25_addr_parse() (minimum 14 address bytes) but carries no control or PID bytes. After ax25_kiss_rcv() strips the KISS framing byte and ax25_rcv() strips the address header with skb_pull(), skb->len drops to zero. The subsequent reads of skb->data[0] (control byte) and skb->data[1] (PID byte) are then out of bounds, which can crash the kernel or leak heap memory to a remote attacker. Use pskb_may_pull(skb, 2) after the skb_pull() to ensure both bytes are in the linear area before reading them. Discard malformed frames that carry no control/PID pair. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Ashutosh Desai --- V2 -> V3: remove incorrect Suggested-by; add symptom, Fixes, Cc stable V1 -> V2: use pskb_may_pull(skb, 2) instead of skb->len < 2 v2: https://lore.kernel.org/netdev/20260409152400.2219716-1-ashutoshdesai993@gmail.com/ v1: https://lore.kernel.org/netdev/20260409012235.2049389-1-ashutoshdesai993@gmail.com/ net/ax25/ax25_in.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/ax25/ax25_in.c b/net/ax25/ax25_in.c index d75b3e9ed93d..6a71dea876a1 100644 --- a/net/ax25/ax25_in.c +++ b/net/ax25/ax25_in.c @@ -217,6 +217,11 @@ static int ax25_rcv(struct sk_buff *skb, struct net_device *dev, */ skb_pull(skb, ax25_addr_size(&dp)); + if (!pskb_may_pull(skb, 2)) { + kfree_skb(skb); + return 0; + } + /* For our port addresses ? */ if (ax25cmp(&dest, dev_addr) == 0 && dp.lastrepeat + 1 == dp.ndigi) mine = 1; -- 2.34.1