Re: general protection fault in __bpf_map_put

[Dmitry Vyukov]

On Wed, Jan 10, 2018 at 1:58 PM, syzbot
<syzbot+d2f5524fb46fd3b312ee@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> 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
>
>
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> Reported-by: syzbot+d2f5524fb46fd3b312ee@xxxxxxxxxxxxxxxxxxxxxxxxx
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Daniel, is it the same bug that was fixed by "bpf, array: fix overflow
in max_entries and undefined behavior in index_mask"?

> 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..
>
>
> ---
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