From patchwork Tue Nov 1 07:33:43 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Baokun Li X-Patchwork-Id: 13026703 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A2F58C433FE for ; Tue, 1 Nov 2022 07:12:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229650AbiKAHMK (ORCPT ); Tue, 1 Nov 2022 03:12:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43760 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229457AbiKAHMJ (ORCPT ); Tue, 1 Nov 2022 03:12:09 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 523423A2; Tue, 1 Nov 2022 00:12:07 -0700 (PDT) Received: from dggpeml500021.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4N1h5v3qVLzHvTL; Tue, 1 Nov 2022 15:11:47 +0800 (CST) Received: from huawei.com (10.175.127.227) by dggpeml500021.china.huawei.com (7.185.36.21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Tue, 1 Nov 2022 15:12:00 +0800 From: Baokun Li To: CC: , , , , , , Subject: [PATCH] squashfs: fix null-ptr-deref in squashfs_fill_super Date: Tue, 1 Nov 2022 15:33:43 +0800 Message-ID: <20221101073343.3961562-1-libaokun1@huawei.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpeml500021.china.huawei.com (7.185.36.21) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org When squashfs_read_table() returns an error or `sb->s_magic != SQUASHFS_MAGIC`, enters the error branch and calls msblk->thread_ops->destroy(msblk) to destroy msblk. However, msblk->thread_ops has not been initialized. Therefore, the following problem is triggered: ================================================================== BUG: KASAN: null-ptr-deref in squashfs_fill_super+0xe7a/0x13b0 Read of size 8 at addr 0000000000000008 by task swapper/0/1 CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.1.0-rc3-next-20221031 #367 Call Trace: dump_stack_lvl+0x73/0x9f print_report+0x743/0x759 kasan_report+0xc0/0x120 __asan_load8+0xd3/0x140 squashfs_fill_super+0xe7a/0x13b0 get_tree_bdev+0x27b/0x450 squashfs_get_tree+0x19/0x30 vfs_get_tree+0x49/0x150 path_mount+0xaae/0x1350 init_mount+0xad/0x100 do_mount_root+0xbc/0x1d0 mount_block_root+0x173/0x316 mount_root+0x223/0x236 prepare_namespace+0x1eb/0x237 kernel_init_freeable+0x528/0x576 kernel_init+0x29/0x250 ret_from_fork+0x1f/0x30 ================================================================== To solve this issue, msblk->thread_ops is initialized immediately after msblk is assigned a value. Fixes: b0645770d3c7 ("squashfs: add the mount parameter theads=") Signed-off-by: Baokun Li Reviewed-by: Xiaoming Ni Reviewed-by: Phillip Lougher --- fs/squashfs/super.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c index 1e428ca9414e..7d5265a39d20 100644 --- a/fs/squashfs/super.c +++ b/fs/squashfs/super.c @@ -197,6 +197,7 @@ static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc) return -ENOMEM; } msblk = sb->s_fs_info; + msblk->thread_ops = opts->thread_ops; msblk->panic_on_errors = (opts->errors == Opt_errors_panic); @@ -231,7 +232,7 @@ static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc) sb->s_bdev); goto failed_mount; } - msblk->thread_ops = opts->thread_ops; + if (opts->thread_num == 0) { msblk->max_thread_num = msblk->thread_ops->max_decompressors(); } else {