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Date:   Tue, 14 Apr 2020 23:55:14 -0700
Message-ID: <000000000000500e6f05a34ecc01@google.com>
Subject: WARNING in bpf_cgroup_link_release
From:   syzbot <syzbot+8a5dadc5c0b1d7055945@syzkaller.appspotmail.com>
To:     andriin@fb.com, ast@kernel.org, bpf@vger.kernel.org,
        daniel@iogearbox.net, john.fastabend@gmail.com, kafai@fb.com,
        kpsingh@chromium.org, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, songliubraving@fb.com,
        syzkaller-bugs@googlegroups.com, yhs@fb.com
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Sender: linux-kernel-owner@vger.kernel.org
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Hello,

syzbot found the following crash on:

HEAD commit:    1a323ea5 x86: get rid of 'errret' argument to __get_user_x..
git tree:       bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=148ccb57e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8c1e98458335a7d1
dashboard link: https://syzkaller.appspot.com/bug?extid=8a5dadc5c0b1d7055945
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
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 25081 Comm: syz-executor.1 Not tainted 5.6.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 panic+0x2e3/0x75c kernel/panic.c:221
 __warn.cold+0x2f/0x35 kernel/panic.c:582
 report_bug+0x27b/0x2f0 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:175 [inline]
 fixup_bug arch/x86/kernel/traps.c:170 [inline]
 do_error_trap+0x12b/0x220 arch/x86/kernel/traps.c:267
 do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:bpf_cgroup_link_release+0x260/0x3a0 kernel/bpf/cgroup.c:796
Code: cf ff 5b 5d 41 5c e9 df 2a e9 ff e8 da 2a e9 ff 48 c7 c7 20 f4 9d 89 e8 de a0 3a 06 5b 5d 41 5c e9 c5 2a e9 ff e8 c0 2a e9 ff <0f> 0b e9 57 fe ff ff e8 a4 3d 26 00 e9 2a fe ff ff e8 9a 3d 26 00
RSP: 0018:ffffc900019a7dc0 EFLAGS: 00010246
RAX: 0000000000040000 RBX: ffff88808c3eac00 RCX: ffffc9000415a000
RDX: 0000000000040000 RSI: ffffffff8189bea0 RDI: 0000000000000005
RBP: 00000000fffffff4 R08: ffff88809055e000 R09: ffffed1015cc70f4
R10: ffffed1015cc70f3 R11: ffff8880ae63879b R12: ffff88808c3eac60
R13: ffff88808c3eac10 R14: ffffc90000f32000 R15: ffffffff817f8e60
 bpf_link_free+0x80/0x140 kernel/bpf/syscall.c:2217
 bpf_link_put+0x15e/0x1b0 kernel/bpf/syscall.c:2243
 bpf_link_release+0x33/0x40 kernel/bpf/syscall.c:2251
 __fput+0x2e9/0x860 fs/file_table.c:280
 task_work_run+0xf4/0x1b0 kernel/task_work.c:123
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2fa/0x360 arch/x86/entry/common.c:165
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
 do_syscall_64+0x6b1/0x7d0 arch/x86/entry/common.c:305
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45c889
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fddaf43fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007fddaf4406d4 RCX: 000000000045c889
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000006
R13: 0000000000000078 R14: 00000000005043d2 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..


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