From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-fw-52002.amazon.com (smtp-fw-52002.amazon.com [52.119.213.150]) (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 A8BA31DEFE7; Wed, 25 Jun 2025 09:50:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=52.119.213.150 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750845056; cv=none; b=KnVI93rw794h1GUpDlvpo3dheB/dgmYmpRBysLWQbIt+J4mX+R3bsTbRn+m9QsJHTRkt7KUvtINNM7cOVk/dTN1hPqXKiXjLUBrEWOt3iVoTs9OBueWg/BzQevg/tMH1tumLbUnD6jJfDxK7DTyJmexfdx5Hyj8fmvq/QILPjVo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750845056; c=relaxed/simple; bh=XV1nkjfUcMxl3FXXMlmgCgmpon5+5Xw73zAFoBzP0nI=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=uGw/TOYap4h80+c9Dmx2wVBP1AuSUSDY72C0RZtQN27FDh2vZ5OG8VOod4nYPR0K+u4K4cXOSdxTJk7wzT/Og+RV6x4YtZgnUyt7WN35/wb2Ten+Ky2GmAvP5QDu2foYUYecIDjsE9NV25YajfvA6Nq7/V0R3tDPhyrmjMun3S0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com; spf=pass smtp.mailfrom=amazon.co.jp; dkim=pass (2048-bit key) header.d=amazon.com header.i=@amazon.com header.b=XGHkEr+3; arc=none smtp.client-ip=52.119.213.150 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.co.jp Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=amazon.com header.i=@amazon.com header.b="XGHkEr+3" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazoncorp2; t=1750845055; x=1782381055; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=i9pQ+MlE5S8O+IzYQuqdhdmkfSkIm+1g1tP/i8TStbQ=; b=XGHkEr+3QYKvlpxVIzCK9sS5bSBFF+CQcuWkoPY1qCV0zlOAnv9joy64 a7SYa/sYk2r6eJO4n8ciJKDBPuM1HllOr/FwBRW37PYYh3NnN2OxhAYyh 5UB5XhCMWuf5zn9aC1w2kB4e2TDsjQrJmfJVuKOQfgVxj+cMPrz6F8KsL MkcWS+T+uiKouYREx4XHAU7gRXN0pTgmEf5qlc0Nl+2wCssko87bZakRB TwXasApLXEXsZSTovsuQhNPknAtua0zIXJmOGanPIeIgpzw/xbttY803r nxI1nDhRmkOLy6vuoKsrz0Won2aSOV/X0LSwv4PER8phskFcysHeHWvAB A==; X-IronPort-AV: E=Sophos;i="6.16,264,1744070400"; d="scan'208";a="736823987" Received: from iad12-co-svc-p1-lb1-vlan3.amazon.com (HELO smtpout.prod.us-west-2.prod.farcaster.email.amazon.dev) ([10.43.8.6]) by smtp-border-fw-52002.iad7.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jun 2025 09:50:29 +0000 Received: from EX19MTAUWB001.ant.amazon.com [10.0.21.151:3829] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.42.18:2525] with esmtp (Farcaster) id b83153d2-cbb2-4d13-bb3b-3d09a4fbbfc7; Wed, 25 Jun 2025 09:50:27 +0000 (UTC) X-Farcaster-Flow-ID: b83153d2-cbb2-4d13-bb3b-3d09a4fbbfc7 Received: from EX19D001UWA001.ant.amazon.com (10.13.138.214) by EX19MTAUWB001.ant.amazon.com (10.250.64.248) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1544.14; Wed, 25 Jun 2025 09:50:26 +0000 Received: from b0be8375a521.amazon.com (10.37.244.14) by EX19D001UWA001.ant.amazon.com (10.13.138.214) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1544.14; Wed, 25 Jun 2025 09:50:24 +0000 From: Kohei Enju To: , CC: "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Kuniyuki Iwashima , Ingo Molnar , Thomas Gleixner , Kohei Enju , Kohei Enju , Subject: [PATCH net v1] rose: fix dangling neighbour pointers in rose_rt_device_down() Date: Wed, 25 Jun 2025 18:49:44 +0900 Message-ID: <20250625095005.66148-2-enjuk@amazon.com> X-Mailer: git-send-email 2.48.1 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-ClientProxiedBy: EX19D040UWA004.ant.amazon.com (10.13.139.93) To EX19D001UWA001.ant.amazon.com (10.13.138.214) There are two bugs in rose_rt_device_down() that can lead to use-after-free: 1. The loop bound `t->count` is modified within the loop, which can cause the loop to terminate early and miss some entries. 2. When removing an entry from the neighbour array, the subsequent entries are moved up to fill the gap, but the loop index `i` is still incremented, causing the next entry to be skipped. For example, if a node has three neighbours (A, B, A) and A is being removed: - 1st iteration (i=0): A is removed, array becomes (B, A, A), count=2 - 2nd iteration (i=1): We now check A instead of B, skipping B entirely - 3rd iteration (i=2): Loop terminates early due to count=2 This leaves the second A in the array with count=2, but the rose_neigh structure has been freed. Accessing code assumes that the first `count` entries are valid pointers, causing a use-after-free when it accesses the dangling pointer. Fix both issues by iterating over the array in reverse order with a fixed loop bound. This ensures that all entries are examined and that the removal of an entry doesn't affect the iteration of subsequent entries. Reported-by: syzbot+e04e2c007ba2c80476cb@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=e04e2c007ba2c80476cb Tested-by: syzbot+e04e2c007ba2c80476cb@syzkaller.appspotmail.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kohei Enju --- net/rose/rose_route.c | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-) diff --git a/net/rose/rose_route.c b/net/rose/rose_route.c index 2dd6bd3a3011..a488fd8c4710 100644 --- a/net/rose/rose_route.c +++ b/net/rose/rose_route.c @@ -479,7 +479,7 @@ void rose_rt_device_down(struct net_device *dev) { struct rose_neigh *s, *rose_neigh; struct rose_node *t, *rose_node; - int i; + int i, j; spin_lock_bh(&rose_node_list_lock); spin_lock_bh(&rose_neigh_list_lock); @@ -497,22 +497,14 @@ void rose_rt_device_down(struct net_device *dev) t = rose_node; rose_node = rose_node->next; - for (i = 0; i < t->count; i++) { + for (i = t->count - 1; i >= 0; i--) { if (t->neighbour[i] != s) continue; t->count--; - switch (i) { - case 0: - t->neighbour[0] = t->neighbour[1]; - fallthrough; - case 1: - t->neighbour[1] = t->neighbour[2]; - break; - case 2: - break; - } + for (j = i; j < t->count; j++) + t->neighbour[j] = t->neighbour[j + 1]; } if (t->count <= 0) -- 2.48.1