general protection fault in iov_iter_fault_in_readable (2)

[syzbot]

Hello,

syzkaller hit the following crash on
968edbd93c0cbb40ab48aca972392d377713a0c3
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.

Unfortunately, I don't have any reproducer for this bug yet.
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org
vi...@zeniv.linux.org.uk]

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
FAULT_FLAG_ALLOW_RETRY missing 30
CPU: 0 PID: 10498 Comm: syz-executor6 Not tainted 4.15.0-rc2+ #212
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x257 lib/dump_stack.c:53
handle_userfault+0x12fa/0x24c0 fs/userfaultfd.c:427
do_anonymous_page mm/memory.c:3121 [inline]
handle_pte_fault mm/memory.c:3934 [inline]
__handle_mm_fault+0x353a/0x3e20 mm/memory.c:4060
handle_mm_fault+0x334/0x8d0 mm/memory.c:4097
__do_page_fault+0x5c9/0xc90 arch/x86/mm/fault.c:1429
do_page_fault+0xee/0x720 arch/x86/mm/fault.c:1504
page_fault+0x22/0x30 arch/x86/entry/entry_64.S:1094
RIP: 0010:fault_in_pages_readable include/linux/pagemap.h:601 [inline]
RIP: 0010:iov_iter_fault_in_readable+0x1a7/0x410 lib/iov_iter.c:421
RSP: 0018:ffff8801d00df928 EFLAGS: 00010246
RAX: 0000000000010000 RBX: 0000000020011fd2 RCX: ffffffff8250b491
RDX: 0000000000000147 RSI: ffffc90002a37000 RDI: ffff8801d00dfd28
RBP: ffff8801d00dfa08 R08: ffff8801c04bedf8 R09: 1ffff1003a01bedf
R10: ffff8801d3dd22c0 R11: 0000000000000003 R12: 1ffff1003a01bf28
R13: ffff8801d00df9e0 R14: 0000000000000000 R15: ffff8801d00dfd20
generic_perform_write+0x200/0x600 mm/filemap.c:3129
__generic_file_write_iter+0x366/0x5b0 mm/filemap.c:3264
generic_file_write_iter+0x399/0x7a0 mm/filemap.c:3292
call_write_iter include/linux/fs.h:1772 [inline]
new_sync_write fs/read_write.c:469 [inline]
__vfs_write+0x68a/0x970 fs/read_write.c:482
vfs_write+0x18f/0x510 fs/read_write.c:544
SYSC_write fs/read_write.c:589 [inline]
SyS_write+0xef/0x220 fs/read_write.c:581
entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x452a39
RSP: 002b:00007f431ffb9c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 0000000000452a39
RDX: 0000000000000030 RSI: 0000000020011fd2 RDI: 0000000000000015
RBP: 0000000000000058 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006ed8e0
R13: 00000000ffffffff R14: 00007f431ffba6d4 R15: 0000000000000000
Dumping ftrace buffer:
(ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 10521 Comm: syz-executor3 Not tainted 4.15.0-rc2+ #212
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:string+0xb4/0x200 lib/vsprintf.c:595
RSP: 0018:ffff8801c8ecf780 EFLAGS: 00010006
RAX: dffffc0000000000 RBX: fffffffffffffffe RCX: ffffffff8513b85f
RDX: 000dccad8dce4e8e RSI: ffffc900037d2000 RDI: ffff8801c8ecf7a0
RBP: ffff8801c8ecf7d0 R08: ffffed003a0eec0e R09: ffffed003a0eec0e
R10: 0000000000000002 R11: ffffed003a0eec0d R12: 006e656c6e727474
R13: 006e656c6e727473 R14: ffffffffffffffff R15: ffff8801d077606a
FS: 00007fe76d67c700(0000) GS:ffff8801db500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000205e2ff0 CR3: 00000001d5abd000 CR4: 00000000001426e0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
vsnprintf+0x863/0x1900 lib/vsprintf.c:2282
seq_vprintf+0xe3/0x1a0 fs/seq_file.c:397
seq_printf+0xb3/0xe0 fs/seq_file.c:412
show_timer+0x1ee/0x2b0 fs/proc/base.c:2274
traverse+0x248/0xa00 fs/seq_file.c:111
seq_read+0x96a/0x13d0 fs/seq_file.c:189
do_loop_readv_writev fs/read_write.c:673 [inline]
do_iter_read+0x3db/0x5b0 fs/read_write.c:897
vfs_readv+0x121/0x1c0 fs/read_write.c:959
do_preadv+0x11b/0x1a0 fs/read_write.c:1043
SYSC_preadv fs/read_write.c:1093 [inline]
SyS_preadv+0x30/0x40 fs/read_write.c:1088
entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x452a39
RSP: 002b:00007fe76d67bc58 EFLAGS: 00000212 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00007fe76d67b950 RCX: 0000000000452a39
RDX: 0000000000000001 RSI: 00000000205e2ff0 RDI: 0000000000000013
RBP: 00007fe76d67b940 R08: 0000000000000000 R09: 0000000000000000
R10: 0001000000000000 R11: 0000000000000212 R12: 00000000004b73a6
R13: 00007fe76d67bac8 R14: 00000000004b73b1 R15: 0000000000000000
Code: 01 00 00 e8 bf 7f 5c fc 4d 85 f6 0f 84 10 01 00 00 e8 b1 7f 5c fc 4c
89 ea 48 b8 00 00 00 00 00 fc ff df 4d 8d 65 01 48 c1 ea 03 <0f> b6 04 02
4c 89 ea 83 e2 07 38 d0 7f 08 84 c0 0f 85 ec 00 00
RIP: string+0xb4/0x200 lib/vsprintf.c:595 RSP: ffff8801c8ecf780
---[ end trace 659778dc7bf2c16b ]---


---
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[Dmitry Vyukov]

#syz invalid

On Mon, Dec 11, 2017 at 7:27 PM, syzbot
<bot+62167437430380a17a...@syzkaller.appspotmail.com>
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