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 X-Spam-Level: X-Spam-Status: No, score=-13.2 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 99A82C433FE for ; Fri, 17 Sep 2021 18:45:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7A40660295 for ; Fri, 17 Sep 2021 18:45:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245720AbhIQSrF (ORCPT ); Fri, 17 Sep 2021 14:47:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242488AbhIQSrE (ORCPT ); Fri, 17 Sep 2021 14:47:04 -0400 Received: from mail-vk1-xa2c.google.com (mail-vk1-xa2c.google.com [IPv6:2607:f8b0:4864:20::a2c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BE199C061574 for ; Fri, 17 Sep 2021 11:45:41 -0700 (PDT) Received: by mail-vk1-xa2c.google.com with SMTP id 13so4077773vkl.1 for ; Fri, 17 Sep 2021 11:45:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=RvSQRCy0ovXt/FmmWH2788dY71Jl29iCo4AO7EInHqg=; b=MXZSuKIFIXGE2SeJq4pv8+OQP6qkexgM5waJOa2JIOUwVK/JSetb6/04DRlLE8mZ6V U67Ztsiz9fLxIQFHDL3ZG+PHJggkJfNN/rUQHRG3yszYaKRsOs4JcWNdXuexUKluWEOT b8edHg7iurIoMdxWs7X4iUOt2rkMW/YV3aCl0GDdg4LeQeP2e/lKFApvxRpEdjqgTY/O aImvGVcZe/dctssX1OGsL/W7i7uI+ef2Di8uFrHlH4pm5ZTn59UUyGWXv0BwT2+p57us iV750i4zcRdV7Hae75MaibCihUAL/hxHNjycybXMGuQ+/si0ciWztcJWlK3s43gLcjQ5 ybNw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=RvSQRCy0ovXt/FmmWH2788dY71Jl29iCo4AO7EInHqg=; b=SCYnRnN1900z3W1EchLS9sPxC612w5mJHYUX83fc/254EY63TDTsPM4hltiVgeqXCu MSmnU+80TiK16seLRCIb9hWhX6xmhh/BgbNgz/rVNjWQZNdWwQTt8VO2G2Zw+iFAKC3H szLxbPD/x19hBgxuCe2Adc923yAbs9gKsQgvQ7gEkQxA8+Yupc0n1NU9jWgTsmHyQLf+ y9aux+6AnFNKuLes7W37XhrnOXXSoYyeFKKLBKolSy+46hvRc9qjmqU7nhXyDTe8JJfR yGQynM2oY2YDh3QQrt3bIlG99k4HDJxemMjy3gG3S8Xz0Oaf4e3p9pTb/foTQpIpUlAd Psow== X-Gm-Message-State: AOAM531u8RTpMPrqyrVzV+4gie95kCvbWLxhorYnqEt4NdD4t59aepOg cYzNONfjxNPsttb4QH2RKkHdW2L7Peav00Gjral81w== X-Google-Smtp-Source: ABdhPJz4GSLeKdIq+YBijrcjm+yTAgO/vW82LHVjl4SVIHIXWHkTLOM1j8NMG+tnPSzmw5b5i3ngVq/xkxr/VHyuDno= X-Received: by 2002:a1f:a006:: with SMTP id j6mr9454879vke.14.1631904340631; Fri, 17 Sep 2021 11:45:40 -0700 (PDT) MIME-Version: 1.0 References: <1M9_d6wrcu6rdPe1ON0_k0lOxJMyyot3KAb1gdyuwzDPC777XVUWPHoTCEVmcK3fYfgu7sIo3PSaLe9KulUdm4TWVuqlbKyYGxRAjsf_Cpk=@protonmail.ch> <87ee9pa6xw.fsf@disp2133> <87zgsb5gaq.fsf@disp2133> In-Reply-To: <87zgsb5gaq.fsf@disp2133> From: Yu Zhao Date: Fri, 17 Sep 2021 12:45:28 -0600 Message-ID: Subject: Re: linux 5.14.3: free_user_ns causes NULL pointer dereference To: "Eric W. Biederman" Cc: Jordan Glover , LKML , "linux-mm@kvack.org" , "legion@kernel.org" , "containers@lists.linux-foundation.org" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 17, 2021 at 10:17 AM Eric W. Biederman wrote: > > Yu Zhao writes: > > > On Wed, Sep 15, 2021 at 4:42 PM Jordan Glover > > wrote: > >> > >> On Wednesday, September 15th, 2021 at 9:02 PM, = wrote: > >> > >> > Jordan Glover Golden_Miller83@protonmail.ch writes: > >> > > >> > > Hi, recently I hit system freeze after I was closing few container= ized apps on my system. As for now it occurred only once on linux 5.14.3. I= think it maybe be related to "Count rlimits in each user namespace" patchs= et merged during 5.14 window > >> > > > >> > > https://lore.kernel.org/all/257aa5fb1a7d81cf0f4c34f39ada2320c42847= 71.1619094428.git.legion@kernel.org/T/#u > >> > > >> > So that warning comes from: > >> > > >> > void dec_ucount(struct ucounts *ucounts, enum ucount_type type) > >> > > >> > { > >> > > >> > struct ucounts *iter; > >> > > >> > for (iter =3D ucounts; iter; iter =3D iter->ns->ucounts) { > >> > > >> > long dec =3D atomic_long_dec_if_positive(&iter->ucount[type]); > >> > > >> > WARN_ON_ONCE(dec < 0); > >> > } > >> > put_ucounts(ucounts); > >> > > >> > > >> > } > >> > > >> > Which certainly looks like a reference count bug. It could also be a > >> > > >> > memory stomp somewhere close. > >> > > >> > Do you have any idea what else was going on? This location is the > >> > > >> > symptom but not the actual cause. > >> > > >> > Eric > >> > >> I had about 2 containerized (flatpak/bubblewrap) apps (browser + music= player) running . I quickly closed them with intent to shutdown the system= but instead get the freeze and had to use magic sysrq to reboot. System lo= gs end with what I posted and before there is nothing suspicious. > >> > >> Maybe it's some random fluke. I'll reply if I hit it again. > > > > I have been able to steadily reproduce this for a while. But I haven't > > had time to look into it. I'd appreciate any help. > > It would be very helpful if you could look farther back in your logs and > see if you can also see: > WARNING: CPU: 1 PID: 351 at kernel/ucount.c:253 dec_ucount+0x43/0x5 > > Or anything else preceding the use-after-free. > > I am inclined to think they are the same issue but without seeing the > WARN_ON_ONCE I can't safely conclude that. It was either the WARN_ON_ONCE or the KASAN before my kernel crashed. (KASAN is on for both cases.) [ 3049.540734] ------------[ cut here ]------------^M [ 3049.545557] WARNING: CPU: 0 PID: 8369 at kernel/ucount.c:253 dec_ucount+0xb0/0xd8^M [ 3049.553293] Modules linked in: vhost_vsock vhost vhost_iotlb vmw_vsock_virtio_transport_common vsock rfcomm algif_hash algif_skcipher af_alg uinput uvcvideo videobuf2_vmalloc venus_enc venus_dec videobuf2_dma_contig videobuf2_memops cros_ec_typec typec hci_uart btqca bluetooth ecdh_generic ecc venus_core v4l2_mem2mem videobuf2_v4l2 videobuf2_common qcom_q6v5_mss ipa qcom_pil_info qcom_q6v5 qcom_common xt_MASQUERADE rmtfs_mem fuse ath10k_snoc qmi_helpers ath10k_core ath mac80211 lzo_rle lzo_compress cfg80211 zram smsc smsc95xx usbnet mii joydev^M [ 3049.603135] CPU: 0 PID: 8369 Comm: kworker/0:2 Not tainted 5.14.0-lockdep+ #4^M [ 3049.610506] Hardware name: Google Lazor (rev3+) with KB Backlight (DT)^M [ 3049.617230] Workqueue: events free_user_ns^M [ 3049.621494] pstate: a0400009 (NzCv daif +PAN -UAO -TCO BTYPE=3D--)^M [ 3049.627694] pc : dec_ucount+0xb0/0xd8^M [ 3049.631489] lr : dec_ucount+0x50/0xd8^M [ 3049.635280] sp : ffffffc019ff7b50^M [ 3049.638707] x29: ffffffc019ff7b50 x28: ffffffd5b5d8b710 x27: ffffff80884cae90^M [ 3049.646083] x26: dfffffc000000000 x25: ffffffd5b5de98a0 x24: 0000000000000001^M [ 3049.653460] x23: ffffff80d2597100 x22: 0000000000000000 x21: dfffffc000000000^M [ 3049.660838] x20: ffffff80d2597120 x19: ffffff80d2597100 x18: 1ffffff01b4b3f48^M [ 3049.668210] x17: 1ffffff01b4b3f47 x16: 0000000000000000 x15: 0000000000000000^M [ 3049.675585] x14: 0000000000000000 x13: 000000002b0cc34b x12: 0000000024966d0f^M [ 3049.682960] x11: 0000000000000000 x10: dfffffc000000001 x9 : 0000000000000000^M [ 3049.690334] x8 : ffffff80d259791f x7 : 0000000000000000 x6 : ffffffd5b3de71c4^M [ 3049.697709] x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffffffd5b3391ca4^M [ 3049.705086] x2 : 0000000000000001 x1 : 0000000000000008 x0 : 0000000000000001^M [ 3049.712459] Call trace:^M [ 3049.715003] dec_ucount+0xb0/0xd8^M [ 3049.718443] free_user_ns+0x1b0/0x288^M [ 3049.722242] process_one_work+0x7b4/0x10ec^M [ 3049.726485] worker_thread+0x800/0xcf4^M [ 3049.730377] kthread+0x2a8/0x358^M [ 3049.733736] ret_from_fork+0x10/0x18^M [ 3049.737445] irq event stamp: 0^M [ 3049.740612] hardirqs last enabled at (0): [<0000000000000000>] 0x0^M [ 3049.747092] hardirqs last disabled at (0): [] copy_process+0xcb0/0x2a54^M [ 3049.755521] softirqs last enabled at (0): [] copy_process+0xcd8/0x2a54^M [ 3049.763954] softirqs last disabled at (0): [<0000000000000000>] 0x0^M [ 3049.770432] ---[ end trace fa55518c981c0c5d ]---^M 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 X-Spam-Level: X-Spam-Status: No, score=-13.2 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0C758C433F5 for ; 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Fri, 17 Sep 2021 18:45:42 +0000 (UTC) X-FDA: 78597944124.24.6E3FB99 Received: from mail-vk1-f174.google.com (mail-vk1-f174.google.com [209.85.221.174]) by imf17.hostedemail.com (Postfix) with ESMTP id C388DF00039F for ; Fri, 17 Sep 2021 18:45:41 +0000 (UTC) Received: by mail-vk1-f174.google.com with SMTP id d10so4049346vke.10 for ; Fri, 17 Sep 2021 11:45:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=RvSQRCy0ovXt/FmmWH2788dY71Jl29iCo4AO7EInHqg=; b=MXZSuKIFIXGE2SeJq4pv8+OQP6qkexgM5waJOa2JIOUwVK/JSetb6/04DRlLE8mZ6V U67Ztsiz9fLxIQFHDL3ZG+PHJggkJfNN/rUQHRG3yszYaKRsOs4JcWNdXuexUKluWEOT b8edHg7iurIoMdxWs7X4iUOt2rkMW/YV3aCl0GDdg4LeQeP2e/lKFApvxRpEdjqgTY/O aImvGVcZe/dctssX1OGsL/W7i7uI+ef2Di8uFrHlH4pm5ZTn59UUyGWXv0BwT2+p57us iV750i4zcRdV7Hae75MaibCihUAL/hxHNjycybXMGuQ+/si0ciWztcJWlK3s43gLcjQ5 ybNw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=RvSQRCy0ovXt/FmmWH2788dY71Jl29iCo4AO7EInHqg=; b=wAvLhr1HftrDpnLoV2vi6qDFXUEeEZvEvcu6zz5QdJawFkH8NpSiI/093EeIO4EXI3 L2aDHYCWN4yZ9vsQQT1RKUPpYgKkWSIxLBk8E5nOGeZ0d7WVc/0TyApq9qwI9KDiOCRi 738HuZU2DZj3w7BvnqoM64fhADc6o9goDf+tMGu52eNE4GaqqiWUbmK7sJc6m7071gP4 6x8m+acpQa1x0r0iYPD4JSfLV3YQPLl7s94Xo/+SFpTYO/26ep22aV2u+H2bgsGp5Y2O v6o1hAmVizo66F7QNrQitMN3juU1nKR9X8+gToMlTrJeymfi+v3VtqNa7PURvRqxem2r 0ndw== X-Gm-Message-State: AOAM53268KLR43p4ojdgtGncb9fs6LZFxPrWD2Og64O4SKOJnAn2lBVS 9dhNkPKTtItdFuTgs/00bEKt9n29WAwrMEllY7nivA== X-Google-Smtp-Source: ABdhPJz4GSLeKdIq+YBijrcjm+yTAgO/vW82LHVjl4SVIHIXWHkTLOM1j8NMG+tnPSzmw5b5i3ngVq/xkxr/VHyuDno= X-Received: by 2002:a1f:a006:: with SMTP id j6mr9454879vke.14.1631904340631; Fri, 17 Sep 2021 11:45:40 -0700 (PDT) MIME-Version: 1.0 References: <1M9_d6wrcu6rdPe1ON0_k0lOxJMyyot3KAb1gdyuwzDPC777XVUWPHoTCEVmcK3fYfgu7sIo3PSaLe9KulUdm4TWVuqlbKyYGxRAjsf_Cpk=@protonmail.ch> <87ee9pa6xw.fsf@disp2133> <87zgsb5gaq.fsf@disp2133> In-Reply-To: <87zgsb5gaq.fsf@disp2133> From: Yu Zhao Date: Fri, 17 Sep 2021 12:45:28 -0600 Message-ID: Subject: Re: linux 5.14.3: free_user_ns causes NULL pointer dereference To: "Eric W. Biederman" Cc: Jordan Glover , LKML , "linux-mm@kvack.org" , "legion@kernel.org" , "containers@lists.linux-foundation.org" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: C388DF00039F X-Stat-Signature: s6gieomzc4zqb9bnhrwbz3wqwh3bswz5 Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=MXZSuKIF; spf=pass (imf17.hostedemail.com: domain of yuzhao@google.com designates 209.85.221.174 as permitted sender) smtp.mailfrom=yuzhao@google.com; dmarc=pass (policy=reject) header.from=google.com X-HE-Tag: 1631904341-497852 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Sep 17, 2021 at 10:17 AM Eric W. Biederman wrote: > > Yu Zhao writes: > > > On Wed, Sep 15, 2021 at 4:42 PM Jordan Glover > > wrote: > >> > >> On Wednesday, September 15th, 2021 at 9:02 PM, = wrote: > >> > >> > Jordan Glover Golden_Miller83@protonmail.ch writes: > >> > > >> > > Hi, recently I hit system freeze after I was closing few container= ized apps on my system. As for now it occurred only once on linux 5.14.3. I= think it maybe be related to "Count rlimits in each user namespace" patchs= et merged during 5.14 window > >> > > > >> > > https://lore.kernel.org/all/257aa5fb1a7d81cf0f4c34f39ada2320c42847= 71.1619094428.git.legion@kernel.org/T/#u > >> > > >> > So that warning comes from: > >> > > >> > void dec_ucount(struct ucounts *ucounts, enum ucount_type type) > >> > > >> > { > >> > > >> > struct ucounts *iter; > >> > > >> > for (iter =3D ucounts; iter; iter =3D iter->ns->ucounts) { > >> > > >> > long dec =3D atomic_long_dec_if_positive(&iter->ucount[type]); > >> > > >> > WARN_ON_ONCE(dec < 0); > >> > } > >> > put_ucounts(ucounts); > >> > > >> > > >> > } > >> > > >> > Which certainly looks like a reference count bug. It could also be a > >> > > >> > memory stomp somewhere close. > >> > > >> > Do you have any idea what else was going on? This location is the > >> > > >> > symptom but not the actual cause. > >> > > >> > Eric > >> > >> I had about 2 containerized (flatpak/bubblewrap) apps (browser + music= player) running . I quickly closed them with intent to shutdown the system= but instead get the freeze and had to use magic sysrq to reboot. System lo= gs end with what I posted and before there is nothing suspicious. > >> > >> Maybe it's some random fluke. I'll reply if I hit it again. > > > > I have been able to steadily reproduce this for a while. But I haven't > > had time to look into it. I'd appreciate any help. > > It would be very helpful if you could look farther back in your logs and > see if you can also see: > WARNING: CPU: 1 PID: 351 at kernel/ucount.c:253 dec_ucount+0x43/0x5 > > Or anything else preceding the use-after-free. > > I am inclined to think they are the same issue but without seeing the > WARN_ON_ONCE I can't safely conclude that. It was either the WARN_ON_ONCE or the KASAN before my kernel crashed. (KASAN is on for both cases.) [ 3049.540734] ------------[ cut here ]------------^M [ 3049.545557] WARNING: CPU: 0 PID: 8369 at kernel/ucount.c:253 dec_ucount+0xb0/0xd8^M [ 3049.553293] Modules linked in: vhost_vsock vhost vhost_iotlb vmw_vsock_virtio_transport_common vsock rfcomm algif_hash algif_skcipher af_alg uinput uvcvideo videobuf2_vmalloc venus_enc venus_dec videobuf2_dma_contig videobuf2_memops cros_ec_typec typec hci_uart btqca bluetooth ecdh_generic ecc venus_core v4l2_mem2mem videobuf2_v4l2 videobuf2_common qcom_q6v5_mss ipa qcom_pil_info qcom_q6v5 qcom_common xt_MASQUERADE rmtfs_mem fuse ath10k_snoc qmi_helpers ath10k_core ath mac80211 lzo_rle lzo_compress cfg80211 zram smsc smsc95xx usbnet mii joydev^M [ 3049.603135] CPU: 0 PID: 8369 Comm: kworker/0:2 Not tainted 5.14.0-lockdep+ #4^M [ 3049.610506] Hardware name: Google Lazor (rev3+) with KB Backlight (DT)^M [ 3049.617230] Workqueue: events free_user_ns^M [ 3049.621494] pstate: a0400009 (NzCv daif +PAN -UAO -TCO BTYPE=3D--)^M [ 3049.627694] pc : dec_ucount+0xb0/0xd8^M [ 3049.631489] lr : dec_ucount+0x50/0xd8^M [ 3049.635280] sp : ffffffc019ff7b50^M [ 3049.638707] x29: ffffffc019ff7b50 x28: ffffffd5b5d8b710 x27: ffffff80884cae90^M [ 3049.646083] x26: dfffffc000000000 x25: ffffffd5b5de98a0 x24: 0000000000000001^M [ 3049.653460] x23: ffffff80d2597100 x22: 0000000000000000 x21: dfffffc000000000^M [ 3049.660838] x20: ffffff80d2597120 x19: ffffff80d2597100 x18: 1ffffff01b4b3f48^M [ 3049.668210] x17: 1ffffff01b4b3f47 x16: 0000000000000000 x15: 0000000000000000^M [ 3049.675585] x14: 0000000000000000 x13: 000000002b0cc34b x12: 0000000024966d0f^M [ 3049.682960] x11: 0000000000000000 x10: dfffffc000000001 x9 : 0000000000000000^M [ 3049.690334] x8 : ffffff80d259791f x7 : 0000000000000000 x6 : ffffffd5b3de71c4^M [ 3049.697709] x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffffffd5b3391ca4^M [ 3049.705086] x2 : 0000000000000001 x1 : 0000000000000008 x0 : 0000000000000001^M [ 3049.712459] Call trace:^M [ 3049.715003] dec_ucount+0xb0/0xd8^M [ 3049.718443] free_user_ns+0x1b0/0x288^M [ 3049.722242] process_one_work+0x7b4/0x10ec^M [ 3049.726485] worker_thread+0x800/0xcf4^M [ 3049.730377] kthread+0x2a8/0x358^M [ 3049.733736] ret_from_fork+0x10/0x18^M [ 3049.737445] irq event stamp: 0^M [ 3049.740612] hardirqs last enabled at (0): [<0000000000000000>] 0x0^M [ 3049.747092] hardirqs last disabled at (0): [] copy_process+0xcb0/0x2a54^M [ 3049.755521] softirqs last enabled at (0): [] copy_process+0xcd8/0x2a54^M [ 3049.763954] softirqs last disabled at (0): [<0000000000000000>] 0x0^M [ 3049.770432] ---[ end trace fa55518c981c0c5d ]---^M