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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Wed, 4 Dec 2019 09:18:16 +0100
Message-ID: <CACT4Y+ZTXKP0MAT3ivr5HO-skZOjSVdz7RbDoyc522_Nbk8nKQ@mail.gmail.com>
Subject: Re: BUG: unable to handle kernel paging request in pcpu_alloc
To:     syzbot <syzbot+82e323920b78d54aaed5@syzkaller.appspotmail.com>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Daniel Axtens <dja@axtens.net>
Cc:     Andrii Nakryiko <andriin@fb.com>,
        Alexei Starovoitov <ast@kernel.org>, bpf <bpf@vger.kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Martin KaFai Lau <kafai@fb.com>,
        LKML <linux-kernel@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>,
        Song Liu <songliubraving@fb.com>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        Yonghong Song <yhs@fb.com>
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Sender: linux-kernel-owner@vger.kernel.org
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On Wed, Dec 4, 2019 at 9:15 AM syzbot
<syzbot+82e323920b78d54aaed5@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    1ab75b2e Add linux-next specific files for 20191203
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=10edf2eae00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=de1505c727f0ec20
> dashboard link: https://syzkaller.appspot.com/bug?extid=82e323920b78d54aaed5
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=156ef061e00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11641edae00000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+82e323920b78d54aaed5@syzkaller.appspotmail.com

+Daniel, is it the same as:
https://syzkaller.appspot.com/bug?id=f6450554481c55c131cc23d581fbd8ea42e63e18
If so, is it possible to make KASAN detect this consistently with the
same crash type so that syzbot does not report duplicates?


> RDX: 000000000000003c RSI: 0000000020000080 RDI: 0c00000000000000
> RBP: 0000000000000000 R08: 0000000000000002 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000018
> R13: 0000000000000004 R14: 0000000000000005 R15: 0000000000000000
> BUG: unable to handle page fault for address: fffff91ffff00000
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x0000) - not-present page
> PGD 21ffe6067 P4D 21ffe6067 PUD aa56c067 PMD aa56d067 PTE 0
> Oops: 0000 [#1] PREEMPT SMP KASAN
> CPU: 1 PID: 8999 Comm: syz-executor865 Not tainted
> 5.4.0-next-20191203-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> RIP: 0010:memory_is_nonzero mm/kasan/generic.c:121 [inline]
> RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:135 [inline]
> RIP: 0010:memory_is_poisoned mm/kasan/generic.c:166 [inline]
> RIP: 0010:check_memory_region_inline mm/kasan/generic.c:182 [inline]
> RIP: 0010:check_memory_region+0x9c/0x1a0 mm/kasan/generic.c:192
> Code: c9 4d 0f 49 c1 49 c1 f8 03 45 85 c0 0f 84 10 01 00 00 41 83 e8 01 4e
> 8d 44 c0 08 eb 0d 48 83 c0 08 4c 39 c0 0f 84 a7 00 00 00 <48> 83 38 00 74
> ed 4c 8d 40 08 eb 09 48 83 c0 01 49 39 c0 74 53 80
> RSP: 0018:ffffc90001f67a80 EFLAGS: 00010216
> RAX: fffff91ffff00000 RBX: fffff91ffff01000 RCX: ffffffff819e1589
> RDX: 0000000000000001 RSI: 0000000000008000 RDI: ffffe8ffff800000
> RBP: ffffc90001f67a98 R08: fffff91ffff01000 R09: 0000000000001000
> R10: fffff91ffff00fff R11: ffffe8ffff807fff R12: fffff91ffff00000
> R13: 0000000000008000 R14: 0000000000000000 R15: ffff88821fffd100
> FS:  00000000011a7880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: fffff91ffff00000 CR3: 00000000a94ad000 CR4: 00000000001406e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>   memset+0x24/0x40 mm/kasan/common.c:107
>   memset include/linux/string.h:410 [inline]
>   pcpu_alloc+0x589/0x1380 mm/percpu.c:1734
>   __alloc_percpu_gfp+0x28/0x30 mm/percpu.c:1783
>   bpf_array_alloc_percpu kernel/bpf/arraymap.c:35 [inline]
>   array_map_alloc+0x698/0x7d0 kernel/bpf/arraymap.c:159
>   find_and_alloc_map kernel/bpf/syscall.c:123 [inline]
>   map_create kernel/bpf/syscall.c:654 [inline]
>   __do_sys_bpf+0x478/0x3810 kernel/bpf/syscall.c:3012
>   __se_sys_bpf kernel/bpf/syscall.c:2989 [inline]
>   __x64_sys_bpf+0x73/0xb0 kernel/bpf/syscall.c:2989
>   do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
>   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x442f99
> Code: e8 ec 09 03 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 cb 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007ffc8aa156d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000442f99
> RDX: 000000000000003c RSI: 0000000020000080 RDI: 0c00000000000000
> RBP: 0000000000000000 R08: 0000000000000002 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000018
> R13: 0000000000000004 R14: 0000000000000005 R15: 0000000000000000
> Modules linked in:
> CR2: fffff91ffff00000
> ---[ end trace 449f8b43dad6ffb8 ]---
> RIP: 0010:memory_is_nonzero mm/kasan/generic.c:121 [inline]
> RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:135 [inline]
> RIP: 0010:memory_is_poisoned mm/kasan/generic.c:166 [inline]
> RIP: 0010:check_memory_region_inline mm/kasan/generic.c:182 [inline]
> RIP: 0010:check_memory_region+0x9c/0x1a0 mm/kasan/generic.c:192
> Code: c9 4d 0f 49 c1 49 c1 f8 03 45 85 c0 0f 84 10 01 00 00 41 83 e8 01 4e
> 8d 44 c0 08 eb 0d 48 83 c0 08 4c 39 c0 0f 84 a7 00 00 00 <48> 83 38 00 74
> ed 4c 8d 40 08 eb 09 48 83 c0 01 49 39 c0 74 53 80
> RSP: 0018:ffffc90001f67a80 EFLAGS: 00010216
> RAX: fffff91ffff00000 RBX: fffff91ffff01000 RCX: ffffffff819e1589
> RDX: 0000000000000001 RSI: 0000000000008000 RDI: ffffe8ffff800000
> RBP: ffffc90001f67a98 R08: fffff91ffff01000 R09: 0000000000001000
> R10: fffff91ffff00fff R11: ffffe8ffff807fff R12: fffff91ffff00000
> R13: 0000000000008000 R14: 0000000000000000 R15: ffff88821fffd100
> FS:  00000000011a7880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: fffff91ffff00000 CR3: 00000000a94ad000 CR4: 00000000001406e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>
>
> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> syzbot can test patches for this bug, for details see:
> https://goo.gl/tpsmEJ#testing-patches
>
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