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 74BAC2E6D28; Tue, 15 Jul 2025 13:26:23 +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=1752585983; cv=none; b=rAfnM5/hdwW1NZreKJwvvW+peLPVRq1ntrigYl54A9XSjujtGG5Xg9HodgDfP7sWNgsgkDwLPpfyKITjvVbgxlRaG0KJx8a/2EPhEV/j90QOMI9m3kzz/bTl7vO0ZrwRnmV/N0QhTGwf7YyKeKNhTIp2Em+/wWWVOLM1pcP8ULQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752585983; c=relaxed/simple; bh=yJU0tN77dJCmQb3rgE6XB9vcfUqMBvrsKvB4Qnk30gY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Z67+A7/wd8k+ItPyEd37NgSLEqlHdGhO/L6ZRYO3AsevZ1b7yuqA5g7RRokSrMITiw7sqjeZPZLOclszR1/6ydE95WYwNHtf116BjYq09Vd9mOWt3hoi3bQWvv/n3MO/kJ8vKBWp9vlXAxnl+F7TzQKVDZy1VdEdg3YedlK6cOQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=c5HvsK24; 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="c5HvsK24" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B6D1BC4CEE3; Tue, 15 Jul 2025 13:26:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1752585983; bh=yJU0tN77dJCmQb3rgE6XB9vcfUqMBvrsKvB4Qnk30gY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=c5HvsK24/AN9mL/tUoMS4Bq61kWFkJ8Ge3NLvgbC9WQ9RCy8yynhWzTNud6U6U38a Oup/5c1qlQDtkGfIjU01SUyE83Q/scjcd9iu0z9KmF08TU74nznMYeREK/+S0GJbAl 3A/nbjXJqZDMxFKOo94XsXgB6G9EFnzyLFBwdlN0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+48240bab47e705c53126@syzkaller.appspotmail.com, Zheng Qixing , Yu Kuai , Jens Axboe , Sasha Levin Subject: [PATCH 6.6 082/109] nbd: fix uaf in nbd_genl_connect() error path Date: Tue, 15 Jul 2025 15:13:38 +0200 Message-ID: <20250715130802.164340872@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250715130758.864940641@linuxfoundation.org> References: <20250715130758.864940641@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zheng Qixing [ Upstream commit aa9552438ebf015fc5f9f890dbfe39f0c53cf37e ] There is a use-after-free issue in nbd: block nbd6: Receive control failed (result -104) block nbd6: shutting down sockets ================================================================== BUG: KASAN: slab-use-after-free in recv_work+0x694/0xa80 drivers/block/nbd.c:1022 Write of size 4 at addr ffff8880295de478 by task kworker/u33:0/67 CPU: 2 UID: 0 PID: 67 Comm: kworker/u33:0 Not tainted 6.15.0-rc5-syzkaller-00123-g2c89c1b655c0 #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Workqueue: nbd6-recv recv_work Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:408 [inline] print_report+0xc3/0x670 mm/kasan/report.c:521 kasan_report+0xe0/0x110 mm/kasan/report.c:634 check_region_inline mm/kasan/generic.c:183 [inline] kasan_check_range+0xef/0x1a0 mm/kasan/generic.c:189 instrument_atomic_read_write include/linux/instrumented.h:96 [inline] atomic_dec include/linux/atomic/atomic-instrumented.h:592 [inline] recv_work+0x694/0xa80 drivers/block/nbd.c:1022 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 nbd_genl_connect() does not properly stop the device on certain error paths after nbd_start_device() has been called. This causes the error path to put nbd->config while recv_work continue to use the config after putting it, leading to use-after-free in recv_work. This patch moves nbd_start_device() after the backend file creation. Reported-by: syzbot+48240bab47e705c53126@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/68227a04.050a0220.f2294.00b5.GAE@google.com/T/ Fixes: 6497ef8df568 ("nbd: provide a way for userspace processes to identify device backends") Signed-off-by: Zheng Qixing Reviewed-by: Yu Kuai Link: https://lore.kernel.org/r/20250612132405.364904-1-zhengqixing@huaweicloud.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- drivers/block/nbd.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 2203686156bfe..3742ddf46c55a 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -2120,9 +2120,7 @@ static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info) goto out; } } - ret = nbd_start_device(nbd); - if (ret) - goto out; + if (info->attrs[NBD_ATTR_BACKEND_IDENTIFIER]) { nbd->backend = nla_strdup(info->attrs[NBD_ATTR_BACKEND_IDENTIFIER], GFP_KERNEL); @@ -2138,6 +2136,8 @@ static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info) goto out; } set_bit(NBD_RT_HAS_BACKEND_FILE, &config->runtime_flags); + + ret = nbd_start_device(nbd); out: mutex_unlock(&nbd->config_lock); if (!ret) { -- 2.39.5