From nobody Fri Jun 19 01:05:51 2026 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 4103EC433F5 for ; Mon, 11 Apr 2022 10:09:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244084AbiDKKLq (ORCPT ); Mon, 11 Apr 2022 06:11:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44226 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229917AbiDKKLo (ORCPT ); Mon, 11 Apr 2022 06:11:44 -0400 Received: from fuzzserver.tsinghua.edu.cn (unknown [166.111.139.106]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 69D28252B2 for ; Mon, 11 Apr 2022 03:09:29 -0700 (PDT) Received: by fuzzserver.tsinghua.edu.cn (Postfix, from userid 1000) id C0C51F40880; Mon, 11 Apr 2022 18:08:57 +0800 (CST) From: Zixuan Fu To: shaggy@kernel.org Cc: jfs-discussion@lists.sourceforge.net, linux-kernel@vger.kernel.org, baijiaju1990@gmail.com, Zixuan Fu , TOTE Robot Subject: [PATCH] fs: jfs: fix possible NULL pointer dereference in dbFree() Date: Mon, 11 Apr 2022 18:08:56 +0800 Message-Id: <20220411100856.693326-1-r33s3n6@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" In our fault-injection testing, the variable "nblocks" in dbFree() can be zero when kmalloc_array() fails in dtSearch(). In this case, the variable "mp" in dbFree() would be NULL and then it is dereferenced in=20 "write_metapage(mp)". The failure log is listed as follows: [ 13.824137] BUG: kernel NULL pointer dereference, address: 0000000000000= 020 ... [ 13.827416] RIP: 0010:dbFree+0x5f7/0x910 [jfs] [ 13.834341] Call Trace: [ 13.834540] [ 13.834713] txFreeMap+0x7b4/0xb10 [jfs] [ 13.835038] txUpdateMap+0x311/0x650 [jfs] [ 13.835375] jfs_lazycommit+0x5f2/0xc70 [jfs] [ 13.835726] ? sched_dynamic_update+0x1b0/0x1b0 [ 13.836092] kthread+0x3c2/0x4a0 [ 13.836355] ? txLockFree+0x160/0x160 [jfs] [ 13.836763] ? kthread_unuse_mm+0x160/0x160 [ 13.837106] ret_from_fork+0x1f/0x30 [ 13.837402] ... This patch adds a NULL check of "mp" before "write_metapage(mp)" is called. Reported-by: TOTE Robot Signed-off-by: Zixuan Fu --- fs/jfs/jfs_dmap.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c index d8502f4989d9..e75f31b81d63 100644 --- a/fs/jfs/jfs_dmap.c +++ b/fs/jfs/jfs_dmap.c @@ -385,7 +385,8 @@ int dbFree(struct inode *ip, s64 blkno, s64 nblocks) } =20 /* write the last buffer. */ - write_metapage(mp); + if (mp) + write_metapage(mp); =20 IREAD_UNLOCK(ipbmap); =20 --=20 2.25.1