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 08:08:12 -1000 [thread overview]
Message-ID: <f496b7cb-5de6-034c-82e1-997b3763f9fc@linaro.org> (raw)
In-Reply-To: <2ecdb36a-adf6-d5b0-8072-2246efdaf99d@linaro.org>
On 2/3/23 07:34, Richard Henderson wrote:
> 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.
Bah, we already do that.
r~
next prev parent reply other threads:[~2023-02-03 18:08 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
2023-02-03 18:08 ` Richard Henderson [this message]
2023-02-03 21:18 ` Richard Henderson
2023-02-04 12:33 ` Anton Johansson via
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