Re: [syzbot] KASAN: vmalloc-out-of-bounds Read in bpf_jit_free

[Daniel Borkmann]

Song, ptal.

On 2/14/22 7:45 PM, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    e5313968c41b Merge branch 'Split bpf_sk_lookup remote_port..
> git tree:       bpf-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=10baced8700000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=c40b67275bfe2a58
> dashboard link: https://syzkaller.appspot.com/bug?extid=2f649ec6d2eea1495a8f
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+2f649ec6d2eea1495a8f@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> ==================================================================
> BUG: KASAN: vmalloc-out-of-bounds in bpf_jit_binary_pack_free kernel/bpf/core.c:1120 [inline]
> BUG: KASAN: vmalloc-out-of-bounds in bpf_jit_free+0x2b5/0x2e0 kernel/bpf/core.c:1151
> Read of size 4 at addr ffffffffa0001a80 by task kworker/0:18/13642
>
> CPU: 0 PID: 13642 Comm: kworker/0:18 Not tainted 5.16.0-syzkaller-11655-ge5313968c41b #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Workqueue: events bpf_prog_free_deferred
> Call Trace:
>   <TASK>
>   __dump_stack lib/dump_stack.c:88 [inline]
>   dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
>   print_address_description.constprop.0.cold+0xf/0x336 mm/kasan/report.c:255
>   __kasan_report mm/kasan/report.c:442 [inline]
>   kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
>   bpf_jit_binary_pack_free kernel/bpf/core.c:1120 [inline]
>   bpf_jit_free+0x2b5/0x2e0 kernel/bpf/core.c:1151
>   bpf_prog_free_deferred+0x5c1/0x790 kernel/bpf/core.c:2524
>   process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307
>   worker_thread+0x657/0x1110 kernel/workqueue.c:2454
>   kthread+0x2e9/0x3a0 kernel/kthread.c:377
>   ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
>   </TASK>
>
>
> Memory state around the buggy address:
>   ffffffffa0001980: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>   ffffffffa0001a00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> > ffffffffa0001a80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>                     ^
>   ffffffffa0001b00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>   ffffffffa0001b80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> ==================================================================
>
>
> ---
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>
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