From: Richard Henderson <richard.henderson@linaro.org>
To: "Alex Bennée" <alex.bennee@linaro.org>, anjo@rev.ng
Cc: qemu-devel@nongnu.org, "ale@rev.ng" <ale@rev.ng>, iii@linux.ibm.com
Subject: Re: ASan reports use-after-free when running munmap-pthread
Date: Fri, 3 Feb 2023 07:34:43 -1000 [thread overview]
Message-ID: <2ecdb36a-adf6-d5b0-8072-2246efdaf99d@linaro.org> (raw)
In-Reply-To: <87wn4zj8kt.fsf@linaro.org>
On 2/3/23 01:23, Alex Bennée wrote:
>
> Anton Johansson <anjo@rev.ng> writes:
>
>> Hi,
>>
>> I was running check-tcg with ASan enabled on master, and ran into
>> the following use-after-free. There appears to be a race between
>> jump cache invalidation and thread destruction (?)
>>
>> I thought I'd post here since I noticed some previous discussion on the
>> topic, and I'm not sure myself what a proper fix would look like.
>
> Something like:
>
> modified accel/tcg/tb-maint.c
> @@ -858,9 +858,7 @@ static void tb_jmp_cache_inval_tb(TranslationBlock *tb)
> CPU_FOREACH(cpu) {
> CPUJumpCache *jc = cpu->tb_jmp_cache;
>
> - if (qatomic_read(&jc->array[h].tb) == tb) {
> - qatomic_set(&jc->array[h].tb, NULL);
> - }
> + qatomic_cmpxchg(&jc->array[h].tb, tb, NULL);
> }
> }
No, this doesn't affect the use-after-free of jc itself.
I think CPUJumpCache needs to be freed with RCU.
r~
next prev parent reply other threads:[~2023-02-03 17:35 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-02 19:06 ASan reports use-after-free when running munmap-pthread Anton Johansson via
2023-02-03 11:23 ` Alex Bennée
2023-02-03 17:34 ` Richard Henderson [this message]
2023-02-03 18:08 ` Richard Henderson
2023-02-03 21:18 ` Richard Henderson
2023-02-04 12:33 ` Anton Johansson via
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