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 A1476C433F5 for ; Wed, 27 Apr 2022 17:22:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237036AbiD0RZK (ORCPT ); Wed, 27 Apr 2022 13:25:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47080 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237253AbiD0RZI (ORCPT ); Wed, 27 Apr 2022 13:25:08 -0400 Received: from mail-pg1-x534.google.com (mail-pg1-x534.google.com [IPv6:2607:f8b0:4864:20::534]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2BC6022294; Wed, 27 Apr 2022 10:21:57 -0700 (PDT) Received: by mail-pg1-x534.google.com with SMTP id k14so1996228pga.0; Wed, 27 Apr 2022 10:21:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=FHxo+FxygLFdesh0y+cuWXYH4w/Nvp0opnXX9bAW478=; b=FZVwPlonHyWXZhkfy3m+C53CKBr9ei5gXCoa/ZIsHd7H/IWlTbRrfP6AVWC+OM+5Be 74nOgjXscouE2Y9eWBH6AHlUHbEIxIyoPanQafetZeVEXPLgZm2S2WqOcr8OlDCpvHZa B1Rt1LfrDENGLWAmL09aAi9NPkib8oFAMqzmveHLmGA9MDcM8Kl7+KDMA/yPZp8i657O IkJvlZ1VrM8bvxJzztWC23lvngAKnT1U6unS9hyzQyFb1x7Wpa60ueSc0KK7pF2X2GjI Uv9PsDlcI6p7XmxtU4hapoezJzfGFL/b55+zIgS93kGBgq1riPObLDRKD8OHE4dmNiEQ hMng== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :mime-version:content-transfer-encoding; bh=FHxo+FxygLFdesh0y+cuWXYH4w/Nvp0opnXX9bAW478=; b=Ai2oANInTlk0LSICZuay4wY9r4zRNUqtYRHODNfEVYYMrn/OMsqLqBeRtqStKhQGhT fACuk6A8MlrO2+XL3HYlL8YzWF45MDBt5wat7+cKZRt0pN/SPhdousr2Y3AMDH1CLWCD CxLAhW1kWaijthsH7WcRY/nQIhA0x1EtdppFaFN+B/hyyDM0Ufkt0kLV/e73UquFpDJs O7wNp3P5JUOIvpdPBnpDDB5txeicw7/p8qDHKmv6jgMpRt5yXjetgJOQFx9BPsPRuMMF cYJVjPAQdNtN3GBKDCX2sC7paHr8ZJa5t8d+hAL2AHjh0cYePmioSJWP7mKLdBgUKmWJ AEEA== X-Gm-Message-State: AOAM532zZ1lzyhiha6N0KbKEBh68qt/2CaPil0Yfjf2zcsf9NRYIXzRd Pe8U4sSGckQER8UjW/K/Koc= X-Google-Smtp-Source: ABdhPJw0XgO/iv4czHtN4DzPOoKpbM/1PXEvF40oShBOL7c7jH5dyBiSFxkZZSKVFZrysUD/Uh+pZA== X-Received: by 2002:a05:6a00:140a:b0:4e0:54d5:d01 with SMTP id l10-20020a056a00140a00b004e054d50d01mr30860409pfu.20.1651080116471; Wed, 27 Apr 2022 10:21:56 -0700 (PDT) Received: from bbox-1.mtv.corp.google.com ([2620:15c:211:201:546a:2875:2a75:1b94]) by smtp.gmail.com with ESMTPSA id iy19-20020a17090b16d300b001cd4989fee6sm7620379pjb.50.2022.04.27.10.21.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Apr 2022 10:21:55 -0700 (PDT) Sender: Minchan Kim From: Minchan Kim To: Greg Kroah-Hartman Cc: Tejun Heo , Jirka Hladky , Thorsten Leemhuis , linux-kernel , regressions@lists.linux.dev, Justin Forbes , Minchan Kim , stable@vger.kernel.org Subject: [PATCH] kernfs: fix NULL dereferencing in kernfs_remove Date: Wed, 27 Apr 2022 10:21:51 -0700 Message-Id: <20220427172152.3505364-1-minchan@kernel.org> X-Mailer: git-send-email 2.36.0.rc2.479.g8af0fa9b8e-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org kernfs_remove supported NULL kernfs_node param to bail out but revent per-fs lock change introduced regression that dereferencing the param without NULL check so kernel goes crash. This patch checks the NULL kernfs_node in kernfs_remove and if so, just return. Quote from bug report by Jirka ``` The bug is triggered by running NAS Parallel benchmark suite on SuperMicro servers with 2x Xeon(R) Gold 6126 CPU. Here is the error log: [ 247.035564] BUG: kernel NULL pointer dereference, address: 0000000000000008 [ 247.036009] #PF: supervisor read access in kernel mode [ 247.036009] #PF: error_code(0x0000) - not-present page [ 247.036009] PGD 0 P4D 0 [ 247.036009] Oops: 0000 [#1] PREEMPT SMP PTI [ 247.058060] CPU: 1 PID: 6546 Comm: umount Not tainted 5.16.0393c3714081a53795bbff0e985d24146def6f57f+ #16 [ 247.058060] Hardware name: Supermicro Super Server/X11DDW-L, BIOS 2.0b 03/07/2018 [ 247.058060] RIP: 0010:kernfs_remove+0x8/0x50 [ 247.058060] Code: 4c 89 e0 5b 5d 41 5c 41 5d 41 5e c3 49 c7 c4 f4 ff ff ff eb b2 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 0f 1f 44 00 00 41 54 55 <48> 8b 47 08 48 89 fd 48 85 c0 48 0f 44 c7 4c 8b 60 50 49 83 c4 60 [ 247.058060] RSP: 0018:ffffbbfa48a27e48 EFLAGS: 00010246 [ 247.058060] RAX: 0000000000000001 RBX: ffffffff89e31f98 RCX: 0000000080200018 [ 247.058060] RDX: 0000000080200019 RSI: fffff6760786c900 RDI: 0000000000000000 [ 247.058060] RBP: ffffffff89e31f98 R08: ffff926b61b24d00 R09: 0000000080200018 [ 247.122048] R10: ffff926b61b24d00 R11: ffff926a8040c000 R12: ffff927bd09a2000 [ 247.122048] R13: ffffffff89e31fa0 R14: dead000000000122 R15: dead000000000100 [ 247.122048] FS: 00007f01be0a8c40(0000) GS:ffff926fa8e40000(0000) knlGS:0000000000000000 [ 247.122048] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 247.122048] CR2: 0000000000000008 CR3: 00000001145c6003 CR4: 00000000007706e0 [ 247.122048] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 247.122048] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 247.122048] PKRU: 55555554 [ 247.122048] Call Trace: [ 247.122048] [ 247.122048] rdt_kill_sb+0x29d/0x350 [ 247.122048] deactivate_locked_super+0x36/0xa0 [ 247.122048] cleanup_mnt+0x131/0x190 [ 247.122048] task_work_run+0x5c/0x90 [ 247.122048] exit_to_user_mode_prepare+0x229/0x230 [ 247.122048] syscall_exit_to_user_mode+0x18/0x40 [ 247.122048] do_syscall_64+0x48/0x90 [ 247.122048] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 247.122048] RIP: 0033:0x7f01be2d735b ``` Cc: stable@vger.kernel.org Link: https://bugzilla.kernel.org/show_bug.cgi?id=215696 Link: https://lore.kernel.org/lkml/CAE4VaGDZr_4wzRn2___eDYRtmdPaGGJdzu_LCSkJYuY9BEO3cw@mail.gmail.com/ Fixes: 393c3714081a (kernfs: switch global kernfs_rwsem lock to per-fs lock) Reported-by: Jirka Hladky Tested-by: Jirka Hladky Signed-off-by: Minchan Kim --- fs/kernfs/dir.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 61a8edc4ba8b..e205fde7163a 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -1406,7 +1406,12 @@ static void __kernfs_remove(struct kernfs_node *kn) */ void kernfs_remove(struct kernfs_node *kn) { - struct kernfs_root *root = kernfs_root(kn); + struct kernfs_root *root; + + if (!kn) + return; + + root = kernfs_root(kn); down_write(&root->kernfs_rwsem); __kernfs_remove(kn); -- 2.36.0.rc2.479.g8af0fa9b8e-goog