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Thu, 16 Apr 2020 15:47:38 -0400 Received: from mail-qv1-xf43.google.com (mail-qv1-xf43.google.com [IPv6:2607:f8b0:4864:20::f43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F05CCC061A0C; Thu, 16 Apr 2020 12:47:37 -0700 (PDT) Received: by mail-qv1-xf43.google.com with SMTP id di6so2672492qvb.10; Thu, 16 Apr 2020 12:47:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=IiQaPOayJr5kvs71qL3IciXFap6VIqNgrywtbyP8RsQ=; b=IAp51LnnxGVluTzeHRtGz8VARjSfnCAjuCl69no0XTQV0d3qD7kTImLBnxzNHa3Qaz na2O5C4U+jjVurGny/iDOZP7DQA94WJJIE15Rb4/gs4fk7T88hJvy/x7XP5FuI/qxtzS fE+IsXIsd3+fpuBTk0KaVYfSTWlzJqd1ZdHdT0mxwxvIxqN/GBau5aX7oJJ1XqDgxtRt 8RH8En9BP7eHgxTcJIgI0ZOb3jIcFVwWqRMzeJmrCZgP+dxyJui8/IIyDIioL1xmjqyQ YGRKCtfvpQUq5RQanOCJ/F8fcbGYrPtufqKpQbSrvgYq3Ic4DNb5iglB6lPSkPGX2utc ux8g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=IiQaPOayJr5kvs71qL3IciXFap6VIqNgrywtbyP8RsQ=; b=Vu6+v4XlBJzyxgDlLz+aXI54l2MyO+7PUQncHbC6P2/wn69pDsmCSBBrP7uACakRcu YGq++2hlCsZpUWDAWq5CMMgZ3IjpH13BRX5FdoDrvKIp4kTjuT9/8YFfh04oMyLWH3Y1 UZ5vgBw/R6btyT5M1xVhJXLD58IxV1/Wijvi3drDSaGLOjMAPpfwCWYMz13ptcwCWlHe ypUyhM8WlPKNtMsJsoJ0UliBbe085XA+oajbwmmoktkKqFfl+iR8xDyyHEAkjKTCcGKK H1jvQjN16VfBfhr0vNnqYG/OfmgmviOjpCCCGqrdbclSpiMZzVM4PGHxjRSwLBJUiyDe PL8g== X-Gm-Message-State: AGi0Pua8s3WcNGp1RMcC07Kiua+HrWKwgkCiq17wCM1ffvIwTrp9cSpH xBSUINojG4Wm7zOaSdyk47+wSvlYPmOiOdV4/TQ= X-Google-Smtp-Source: APiQypKtquRwWQQXFqOBPvTZeBbMC3tNNdEXbLRDwIg2ysD7zcUg4ZsrG/9Ggfv0t+EXh+ucnxtI3C2lYt6SlX8rXiA= X-Received: by 2002:a0c:fd8c:: with SMTP id p12mr12042055qvr.163.1587066457100; Thu, 16 Apr 2020 12:47:37 -0700 (PDT) MIME-Version: 1.0 References: <000000000000500e6f05a34ecc01@google.com> <4ba5ee0c-ec81-8ce3-6681-465e34b98a93@iogearbox.net> <20200416102612.GO1163@kadam> In-Reply-To: <20200416102612.GO1163@kadam> From: Andrii Nakryiko Date: Thu, 16 Apr 2020 12:47:25 -0700 Message-ID: Subject: Re: WARNING in bpf_cgroup_link_release To: Dan Carpenter Cc: Andrii Nakryiko , Daniel Borkmann , syzbot , Alexei Starovoitov , bpf , john fastabend , Martin Lau , KP Singh , open list , Networking , Song Liu , syzkaller-bugs@googlegroups.com, Yonghong Song Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 16, 2020 at 3:29 AM Dan Carpenter wr= ote: > > On Wed, Apr 15, 2020 at 09:51:40AM -0700, 'Andrii Nakryiko' via syzkaller= -bugs wrote: > > On 4/15/20 4:57 AM, Daniel Borkmann wrote: > > > On 4/15/20 8:55 AM, syzbot wrote: > > > > Hello, > > > > > > > > syzbot found the following crash on: > > > > > > Andrii, ptal. > > > > > > > HEAD commit: 1a323ea5 x86: get rid of 'errret' argument to > > > > __get_user_x.. > > > > git tree: bpf-next > > > > console output: https://urldefense.proofpoint.com/v2/url?u=3Dhttps-= 3A__syzkaller.appspot.com_x_log.txt-3Fx-3D148ccb57e00000&d=3DDwICaQ&c=3D5VD= 0RTtNlTh3ycd41b3MUw&r=3Dvxqvl81C2rT6GOGdPyz8iQ&m=3DT2Ez0XmyIpHmEa_MPTTUOh61= jMDXqwETtTaTbSe-2M4&s=3D-6XBbsNV1O4X5flrx4Yssfjc56d0qeSHgwHhd92UPJc&e=3D > > > > kernel config: https://urldefense.proofpoint.com/v2/url?u=3Dhttps-= 3A__syzkaller.appspot.com_x_.config-3Fx-3D8c1e98458335a7d1&d=3DDwICaQ&c=3D5= VD0RTtNlTh3ycd41b3MUw&r=3Dvxqvl81C2rT6GOGdPyz8iQ&m=3DT2Ez0XmyIpHmEa_MPTTUOh= 61jMDXqwETtTaTbSe-2M4&s=3Ds5-1AlWtSiBvo66WN4_UXoXMGIGIqsoUCrmAnxNnfX0&e=3D > > > > dashboard link: https://urldefense.proofpoint.com/v2/url?u=3Dhttps-= 3A__syzkaller.appspot.com_bug-3Fextid-3D8a5dadc5c0b1d7055945&d=3DDwICaQ&c= =3D5VD0RTtNlTh3ycd41b3MUw&r=3Dvxqvl81C2rT6GOGdPyz8iQ&m=3DT2Ez0XmyIpHmEa_MPT= TUOh61jMDXqwETtTaTbSe-2M4&s=3DhAA0702qJH5EwRwvG0RKmj8FwIRm1O8hvmoS7ne5Dls&e= =3D > > > > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > > > > > > > Unfortunately, I don't have any reproducer for this crash yet. > > > > > > > > IMPORTANT: if you fix the bug, please add the following tag to the > > > > commit: > > > > Reported-by: syzbot+8a5dadc5c0b1d7055945@syzkaller.appspotmail.com > > > > > > > > ------------[ cut here ]------------ > > > > WARNING: CPU: 0 PID: 25081 at kernel/bpf/cgroup.c:796 > > > > bpf_cgroup_link_release+0x260/0x3a0 kernel/bpf/cgroup.c:796 > > > > This warning is triggered due to __cgroup_bpf_detach returning an error= . It > > can do it only in two cases: either attached item is not found, which f= rom > > starting at code some moreI don't see how that can happen. The other re= ason > > - kmalloc() failing to allocate memory for new effective prog array. > > If you look at the log file then this was allocation fault injection in > bpf_prog_array_alloc(). Ah, I see, thanks for pointing this out! So that confirms that it's not a bug, but just unfortunate result of potentially failing cgroup BPF program detach code path. > > https://syzkaller.appspot.com/x/log.txt?x=3D148ccb57e00000 > > regards, > dan carpenter >