Message-ID: <000000000000ca5b3f0596a21e0c@google.com>
Date:   Tue, 05 Nov 2019 15:52:08 -0800
From:   syzbot <syzbot+a0fc447639c6ffa66b59@...kaller.appspotmail.com>
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Subject: general protection fault in pagemap_pmd_range

Hello,

syzbot found the following crash on:

HEAD commit:    51309b9d Add linux-next specific files for 20191105
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=11ad1658e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a9b1a641c1f1fc52
dashboard link: https://syzkaller.appspot.com/bug?extid=a0fc447639c6ffa66b59
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=164e5f92e00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15c65bcce00000

The bug was bisected to:

commit 181be542ef3c9ca495500143d4c23f4d58beb5ab
Author: Steven Price <steven.price@....com>
Date:   Mon Nov 4 22:57:54 2019 +0000

     mm: pagewalk: allow walking without vma

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=11341968e00000
final crash:    https://syzkaller.appspot.com/x/report.txt?x=13341968e00000
console output: https://syzkaller.appspot.com/x/log.txt?x=15341968e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+a0fc447639c6ffa66b59@...kaller.appspotmail.com
Fixes: 181be542ef3c ("mm: pagewalk: allow walking without vma")

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: 0 PID: 8839 Comm: syz-executor009 Not tainted 5.4.0-rc6-next-20191105  
#0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:pmd_trans_huge_lock include/linux/huge_mm.h:219 [inline]
RIP: 0010:pagemap_pmd_range+0x83/0x1e40 fs/proc/task_mmu.c:1373
Code: c1 ea 03 80 3c 02 00 0f 85 ef 1a 00 00 48 8b 43 18 49 8d 7f 40 48 89  
fa 48 c1 ea 03 48 89 45 c8 48 b8 00 00 00 00 00 fc ff df <80> 3c 02 00 0f  
85 be 1a 00 00 49 8b 5f 40 be 08 00 00 00 4c 8d ab
RSP: 0018:ffff8880a4e4f288 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff8880a4e4f438 RCX: ffff8880a4e4f438
RDX: 0000000000000008 RSI: ffffffff81dd1b94 RDI: 0000000000000040
RBP: ffff8880a4e4f300 R08: ffff8880992ee040 R09: ffffed1012180ad2
R10: ffffed1012180ad1 R11: ffff888090c0568b R12: ffff8880a53a2010
R13: 0000000000600000 R14: 00000000005fffff R15: 0000000000000000
FS:  000000000172c880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000455150 CR3: 000000009f949000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  walk_pmd_range mm/pagewalk.c:78 [inline]
  walk_pud_range mm/pagewalk.c:149 [inline]
  walk_p4d_range mm/pagewalk.c:190 [inline]
  walk_pgd_range mm/pagewalk.c:223 [inline]
  __walk_page_range+0x10ff/0x1b40 mm/pagewalk.c:318
  walk_page_range+0x1c5/0x3b0 mm/pagewalk.c:406
  pagemap_read+0x4d1/0x650 fs/proc/task_mmu.c:1596
  do_loop_readv_writev fs/read_write.c:714 [inline]
  do_loop_readv_writev fs/read_write.c:701 [inline]
  do_iter_read+0x4a4/0x660 fs/read_write.c:935
  vfs_readv+0xf0/0x160 fs/read_write.c:997
  kernel_readv fs/splice.c:359 [inline]
  default_file_splice_read+0x482/0x8a0 fs/splice.c:414
  do_splice_to+0x127/0x180 fs/splice.c:877
  splice_direct_to_actor+0x2d3/0x970 fs/splice.c:955
  do_splice_direct+0x1da/0x2a0 fs/splice.c:1064
  do_sendfile+0x597/0xd00 fs/read_write.c:1464
  __do_sys_sendfile64 fs/read_write.c:1525 [inline]
  __se_sys_sendfile64 fs/read_write.c:1511 [inline]
  __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1511
  do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4401e9
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 5b 14 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffcb2c0cd38 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004401e9
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000012 R09: 65732f636f72702f
R10: 0000100000206201 R11: 0000000000000246 R12: 0000000000401ad0
R13: 0000000000401b60 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace d938329fe3462ca9 ]---
RIP: 0010:pmd_trans_huge_lock include/linux/huge_mm.h:219 [inline]
RIP: 0010:pagemap_pmd_range+0x83/0x1e40 fs/proc/task_mmu.c:1373
Code: c1 ea 03 80 3c 02 00 0f 85 ef 1a 00 00 48 8b 43 18 49 8d 7f 40 48 89  
fa 48 c1 ea 03 48 89 45 c8 48 b8 00 00 00 00 00 fc ff df <80> 3c 02 00 0f  
85 be 1a 00 00 49 8b 5f 40 be 08 00 00 00 4c 8d ab
RSP: 0018:ffff8880a4e4f288 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff8880a4e4f438 RCX: ffff8880a4e4f438
RDX: 0000000000000008 RSI: ffffffff81dd1b94 RDI: 0000000000000040
RBP: ffff8880a4e4f300 R08: ffff8880992ee040 R09: ffffed1012180ad2
R10: ffffed1012180ad1 R11: ffff888090c0568b R12: ffff8880a53a2010
R13: 0000000000600000 R14: 00000000005fffff R15: 0000000000000000
FS:  000000000172c880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000455150 CR3: 000000009f949000 CR4: 00000000001406f0
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@...glegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

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