Re: [syzbot] [bpf?] KASAN: stack-out-of-bounds Read in hash

[Hou Tao]

Hi,

On 4/7/2024 10:24 PM, Alexei Starovoitov wrote:
> On Sun, Apr 7, 2024 at 2:09 AM Hou Tao <houtao@xxxxxxxxxxxxxxx> wrote:
>> Hi,
>>
>> On 4/6/2024 9:44 PM, syzbot wrote:
>>> Hello,
>>>
>>> syzbot found the following issue on:
>>>
>>> HEAD commit:    443574b03387 riscv, bpf: Fix kfunc parameters incompatibil..
>>> git tree:       bpf
>>> console+strace: https://syzkaller.appspot.com/x/log.txt?x=148ad855180000
>>> kernel config:  https://syzkaller.appspot.com/x/.config?x=6fb1be60a193d440
>>> dashboard link: https://syzkaller.appspot.com/bug?extid=9459b5d7fab774cf182f
>>> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
>>> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13d86795180000
>>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=143eff76180000
>> According to the reproducer, it passes a big value_size (0xfffffe00)
>> when creating bloom filter map. The big value_size bypasses the check in
>> check_stack_access_within_bounds(). I think a proper fix needs to add
>> these following two checks:
>> (1) in check_stack_access_within_bounds()  add check for negative
>> access_size
>> (2) in bloom_map_alloc() limit the max value of bloom_map_alloc().
>>
>> Will post a patch to fix the syzbot report. Will also check whether or
>> not there are similar problems for other bpf maps.
> Isn't it fixed by
> https://lore.kernel.org/all/20240327024245.318299-2-andreimatei1@xxxxxxxxx/

Yes. Totally missed the patch set. The patch set will fix the syzbot
reported problem.