Subject: general protection fault in __bpf_map_put

From: syzbot <[email-masked]>
Date: Wed, 10 Jan 2018 04:58:02 -0800

Hello,

syzkaller hit the following crash on  
b4464bcab38d3f7fe995a7cb960eeac6889bec08
git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.
C reproducer is attached
syzkaller reproducer is attached. See https://goo.gl/kgGztJ
for information about syzkaller reproducers

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: [email-masked]
It will help syzbot understand when the bug is fixed. See footer for  
details.
If you forward the report, please keep this part and the footer.

audit: type=1400 audit(1515571663.627:11): avc:  denied  { map_read  
map_write } for  pid=3537 comm="syzkaller597104"  
scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023  
tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=bpf  
permissive=1
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
Dumping ftrace buffer:
    (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 23 Comm: kworker/1:1 Not tainted 4.15.0-rc7-next-20180110+ #93
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: events bpf_map_free_deferred
RIP: 0010:__bpf_map_put+0x64/0x2e0 kernel/bpf/syscall.c:233
RSP: 0018:ffff8801d98b7458 EFLAGS: 00010293
RAX: ffff8801d98ac600 RBX: ad6001bc00000dd1 RCX: ffffffff817e4454
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ad6001bc00000dd1
RBP: ffff8801d98b74e8 R08: 1ffff1003b316e6a R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff1003b316e8c
R13: dffffc0000000000 R14: dffffc0000000000 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000204f9fe4 CR3: 0000000006822003 CR4: 00000000001606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  bpf_map_put+0x1a/0x20 kernel/bpf/syscall.c:243
  bpf_map_fd_put_ptr+0x15/0x20 kernel/bpf/map_in_map.c:96
  fd_array_map_delete_elem kernel/bpf/arraymap.c:420 [inline]
  bpf_fd_array_map_clear kernel/bpf/arraymap.c:461 [inline]
  array_of_map_free+0x100/0x180 kernel/bpf/arraymap.c:618
  bpf_map_free_deferred+0xb0/0xe0 kernel/bpf/syscall.c:217
  process_one_work+0xbbf/0x1af0 kernel/workqueue.c:2112
  worker_thread+0x223/0x1990 kernel/workqueue.c:2246
  kthread+0x33c/0x400 kernel/kthread.c:238
  ret_from_fork+0x4b/0x60 arch/x86/entry/entry_64.S:547
Code: b5 41 48 c7 45 80 1d 2c 59 86 48 c7 45 88 f0 43 7e 81 c7 00 f1 f1 f1  
f1 c7 40 04 00 f2 f2 f2 c7 40 08 f3 f3 f3 f3 e8 9c 1e f2 ff <f0> ff 4b 48  
74 2f e8 91 1e f2 ff 48 b8 00 00 00 00 00 fc ff df
RIP: __bpf_map_put+0x64/0x2e0 kernel/bpf/syscall.c:233 RSP: ffff8801d98b7458
---[ end trace 61592f27aaa1e096 ]---
Kernel panic - not syncing: Fatal exception
Dumping ftrace buffer:
    (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..

---
This bug is generated by a dumb bot. It may contain errors.
See https://goo.gl/tpsmEJ for details.
Direct all questions to [email-masked].

syzbot will keep track of this bug report.
If you forgot to add the Reported-by tag, once the fix for this bug is  
merged
into any tree, please reply to this email with:
#syz fix: exact-commit-title
If you want to test a patch for this bug, please reply with:
#syz test: git://repo/address.git branch
and provide the patch inline or as an attachment.
To mark this as a duplicate of another syzbot report, please reply with:
#syz dup: exact-subject-of-another-report
If it's a one-off invalid bug report, please reply with:
#syz invalid
Note: if the crash happens again, it will cause creation of a new bug  
report.
Note: all commands must start from beginning of the line in the email body.