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Date:   Mon, 19 Aug 2019 18:18:06 -0700
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Subject: general protection fault in xsk_poll
From:   syzbot <syzbot+c82697e3043781e08802@syzkaller.appspotmail.com>
To:     ast@kernel.org, bjorn.topel@intel.com, bpf@vger.kernel.org,
        daniel@iogearbox.net, davem@davemloft.net, hawk@kernel.org,
        jakub.kicinski@netronome.com, john.fastabend@gmail.com,
        jonathan.lemon@gmail.com, kafai@fb.com,
        linux-kernel@vger.kernel.org, magnus.karlsson@intel.com,
        netdev@vger.kernel.org, songliubraving@fb.com,
        syzkaller-bugs@googlegroups.com, xdp-newbies@vger.kernel.org,
        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:    da657043 Add linux-next specific files for 20190819
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16af124c600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=739a9b3ab3d8c770
dashboard link: https://syzkaller.appspot.com/bug?extid=c82697e3043781e08802
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=109e1922600000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1445bf02600000

The bug was bisected to:

commit 77cd0d7b3f257fd0e3096b4fdcff1a7d38e99e10
Author: Magnus Karlsson <magnus.karlsson@intel.com>
Date:   Wed Aug 14 07:27:17 2019 +0000

     xsk: add support for need_wakeup flag in AF_XDP rings

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=15e1ea4c600000
final crash:    https://syzkaller.appspot.com/x/report.txt?x=17e1ea4c600000
console output: https://syzkaller.appspot.com/x/log.txt?x=13e1ea4c600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+c82697e3043781e08802@syzkaller.appspotmail.com
Fixes: 77cd0d7b3f25 ("xsk: add support for need_wakeup flag in AF_XDP  
rings")

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 7959 Comm: syz-executor611 Not tainted 5.3.0-rc5-next-20190819  
#68
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:xsk_poll+0x95/0x540 net/xdp/xsk.c:386
Code: 80 3c 02 00 0f 85 70 04 00 00 4c 8b a3 88 04 00 00 48 b8 00 00 00 00  
00 fc ff df 49 8d bc 24 96 00 00 00 48 89 fa 48 c1 ea 03 <0f> b6 04 02 48  
89 fa 83 e2 07 38 d0 7f 08 84 c0 0f 85 bf 03 00 00
RSP: 0018:ffff8880926f7850 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff88809a141700 RCX: ffffffff859b07aa
RDX: 0000000000000012 RSI: ffffffff859b07c4 RDI: 0000000000000096
RBP: ffff8880926f7880 R08: ffff88809698a580 R09: ffffed1013428329
R10: ffffed1013428328 R11: ffff88809a141947 R12: 0000000000000000
R13: 0000000000000304 R14: ffff888095d4d840 R15: ffff888092bdd020
FS:  0000555557529880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000280 CR3: 0000000098281000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  sock_poll+0x15e/0x480 net/socket.c:1256
  vfs_poll include/linux/poll.h:90 [inline]
  do_pollfd fs/select.c:859 [inline]
  do_poll fs/select.c:907 [inline]
  do_sys_poll+0x7c2/0xde0 fs/select.c:1001
  __do_sys_ppoll fs/select.c:1101 [inline]
  __se_sys_ppoll fs/select.c:1081 [inline]
  __x64_sys_ppoll+0x259/0x310 fs/select.c:1081
  do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x440159
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffd9fbd16e8 EFLAGS: 00000246 ORIG_RAX: 000000000000010f
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440159
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000020000280
RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004019e0
R13: 0000000000401a70 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace da907175426b4065 ]---
RIP: 0010:xsk_poll+0x95/0x540 net/xdp/xsk.c:386
Code: 80 3c 02 00 0f 85 70 04 00 00 4c 8b a3 88 04 00 00 48 b8 00 00 00 00  
00 fc ff df 49 8d bc 24 96 00 00 00 48 89 fa 48 c1 ea 03 <0f> b6 04 02 48  
89 fa 83 e2 07 38 d0 7f 08 84 c0 0f 85 bf 03 00 00
RSP: 0018:ffff8880926f7850 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff88809a141700 RCX: ffffffff859b07aa
RDX: 0000000000000012 RSI: ffffffff859b07c4 RDI: 0000000000000096
RBP: ffff8880926f7880 R08: ffff88809698a580 R09: ffffed1013428329
R10: ffffed1013428328 R11: ffff88809a141947 R12: 0000000000000000
R13: 0000000000000304 R14: ffff888095d4d840 R15: ffff888092bdd020
FS:  0000555557529880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000280 CR3: 0000000098281000 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.
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this bug, for details see:
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