From mboxrd@z Thu Jan 1 00:00:00 1970 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 A71F9EEB585 for ; Sat, 9 Sep 2023 10:14:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344489AbjIIKOu (ORCPT ); Sat, 9 Sep 2023 06:14:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55400 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229529AbjIIKOu (ORCPT ); Sat, 9 Sep 2023 06:14:50 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AE91F10DF for ; Sat, 9 Sep 2023 03:14:44 -0700 (PDT) Received: from kwepemi500008.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4RjTJg4P09zNmpr; Sat, 9 Sep 2023 18:10:59 +0800 (CST) Received: from [10.67.109.254] (10.67.109.254) by kwepemi500008.china.huawei.com (7.221.188.139) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Sat, 9 Sep 2023 18:14:40 +0800 Message-ID: Date: Sat, 9 Sep 2023 18:14:40 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [PATCH v2] eventfs: Fix the NULL pointer dereference bug in eventfs_remove_rec() Content-Language: en-US To: "Masami Hiramatsu (Google)" CC: , Steven Rostedt , Ajay Kaher References: <20230909072817.182846-1-ruanjinjie@huawei.com> <20230909184830.8a62399dbeeda70199153a37@kernel.org> From: Ruan Jinjie In-Reply-To: <20230909184830.8a62399dbeeda70199153a37@kernel.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.109.254] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To kwepemi500008.china.huawei.com (7.221.188.139) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org On 2023/9/9 17:48, Masami Hiramatsu (Google) wrote: > On Sat, 9 Sep 2023 15:28:16 +0800 > Jinjie Ruan wrote: > >> Inject fault while probing btrfs.ko, if kstrdup() fails in >> eventfs_prepare_ef() in eventfs_add_dir(), it will return ERR_PTR >> to assign file->ef. But the eventfs_remove() check NULL in >> trace_module_remove_events(), which causes the below NULL >> pointer dereference. >> >> As both Masami and Steven suggest, use IS_ERR_OR_NULL() to >> check ef in eventfs_remove_rec(), and fix the same issue >> in eventfs_remove(). >> >> Could not create tracefs 'raid56_write' directory >> Btrfs loaded, zoned=no, fsverity=no >> Unable to handle kernel NULL pointer dereference at virtual address 000000000000001c >> Mem abort info: >> ESR = 0x0000000096000004 >> EC = 0x25: DABT (current EL), IL = 32 bits >> SET = 0, FnV = 0 >> EA = 0, S1PTW = 0 >> FSC = 0x04: level 0 translation fault >> Data abort info: >> ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 >> CM = 0, WnR = 0, TnD = 0, TagAccess = 0 >> GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 >> user pgtable: 4k pages, 48-bit VAs, pgdp=0000000102544000 >> [000000000000001c] pgd=0000000000000000, p4d=0000000000000000 >> Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP >> Dumping ftrace buffer: >> (ftrace buffer empty) >> Modules linked in: btrfs(-) libcrc32c xor xor_neon raid6_pq cfg80211 rfkill 8021q garp mrp stp llc ipv6 [last unloaded: btrfs] >> CPU: 15 PID: 1343 Comm: rmmod Tainted: G N 6.5.0+ #40 >> Hardware name: linux,dummy-virt (DT) >> pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) >> pc : eventfs_remove_rec+0x24/0xc0 >> lr : eventfs_remove+0x68/0x1d8 >> sp : ffff800082d63b60 >> x29: ffff800082d63b60 x28: ffffb84b80ddd00c x27: ffffb84b3054ba40 >> x26: 0000000000000002 x25: ffff800082d63bf8 x24: ffffb84b8398e440 >> x23: ffffb84b82af3000 x22: dead000000000100 x21: dead000000000122 >> x20: ffff800082d63bf8 x19: fffffffffffffff4 x18: ffffb84b82508820 >> x17: 0000000000000000 x16: 0000000000000000 x15: 000083bc876a3166 >> x14: 000000000000006d x13: 000000000000006d x12: 0000000000000000 >> x11: 0000000000000001 x10: 00000000000017e0 x9 : 0000000000000001 >> x8 : 0000000000000000 x7 : 0000000000000000 x6 : ffffb84b84289804 >> x5 : 0000000000000000 x4 : 9696969696969697 x3 : ffff33a5b7601f38 >> x2 : 0000000000000000 x1 : ffff800082d63bf8 x0 : fffffffffffffff4 >> Call trace: >> eventfs_remove_rec+0x24/0xc0 >> eventfs_remove+0x68/0x1d8 >> remove_event_file_dir+0x88/0x100 >> event_remove+0x140/0x15c >> trace_module_notify+0x1fc/0x230 >> notifier_call_chain+0x98/0x17c >> blocking_notifier_call_chain+0x4c/0x74 >> __arm64_sys_delete_module+0x1a4/0x298 >> invoke_syscall+0x44/0x100 >> el0_svc_common.constprop.1+0x68/0xe0 >> do_el0_svc+0x1c/0x28 >> el0_svc+0x3c/0xc4 >> el0t_64_sync_handler+0xa0/0xc4 >> el0t_64_sync+0x174/0x178 >> Code: 5400052c a90153b3 aa0003f3 aa0103f4 (f9401400) >> ---[ end trace 0000000000000000 ]--- >> Kernel panic - not syncing: Oops: Fatal exception >> SMP: stopping secondary CPUs >> Dumping ftrace buffer: >> (ftrace buffer empty) >> Kernel Offset: 0x384b00c00000 from 0xffff800080000000 >> PHYS_OFFSET: 0xffffcc5b80000000 >> CPU features: 0x88000203,3c020000,1000421b >> Memory Limit: none >> Rebooting in 1 seconds.. >> >> Fixes: 5bdcd5f5331a ("eventfs: Implement removal of meta data from eventfs") >> Signed-off-by: Jinjie Ruan >> Suggested-by: Masami Hiramatsu (Google) >> Suggested-by: Steven Rostedt >> --- >> v2: >> - Use IS_ERR_OR_NULL() to check instead of IS_ERR() as suggested. >> - Update the commit message. >> --- >> fs/tracefs/event_inode.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c >> index 237c6f370ad9..c354b6013881 100644 >> --- a/fs/tracefs/event_inode.c >> +++ b/fs/tracefs/event_inode.c >> @@ -693,7 +693,7 @@ static void eventfs_remove_rec(struct eventfs_file *ef, struct list_head *head, >> { >> struct eventfs_file *ef_child; >> >> - if (!ef) >> + if (IS_ERR_OR_NULL(ef)) > > Sorry, I think `ef` must not be an error value because in between the allocation > and this removing, some code can accidentary access it because it is not NULL. > > I think the allocator must set NULL, if it's not, it should be warned. > > if (!ef || WARN_ON_ONCE(IS_ERR(ef))) > return; > > Of course this still cause a warning, so fix the eventfs_add_dir() too. > (But fixing the eventfs_add_dir() will remove the error, we may not need > this WARN_ON_ONCE() here.) > Or, any other path did you find which sets ef=ERR_PTR(err)? Not found so far. > > Thanks, > >> return; >> /* >> * Check recursion depth. It should never be greater than 3: >> @@ -730,7 +730,7 @@ void eventfs_remove(struct eventfs_file *ef) >> struct dentry *dentry_list = NULL; >> struct dentry *dentry; >> >> - if (!ef) >> + if (IS_ERR_OR_NULL(ef)) >> return; >> >> mutex_lock(&eventfs_mutex); >> -- >> 2.34.1 >> > >