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From: "Philippe Mathieu-Daudé" <f4bug@amsat.org>
To: Richard Purdie <richard.purdie@linuxfoundation.org>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Cc: Laurent Vivier <laurent@vivier.eu>
Subject: Re: [RFC PATCH] linux-user/mmap: Return EFAULT for invalid addresses
Date: Fri, 22 Jan 2021 11:28:45 +0100	[thread overview]
Message-ID: <5b84c555-04ec-f85e-b90d-4cbaf0f7c355@amsat.org> (raw)
In-Reply-To: <d4ea76d141067563c24aacc99dab9aa753cd55a2.camel@linuxfoundation.org>

Cc'ing maintainer

On 1/22/21 10:37 AM, Richard Purdie wrote:
> On Fri, 2021-01-08 at 17:46 +0000, Richard Purdie wrote:
>> When using qemu-i386 to run gobject introspection parts of a webkitgtk 
>> build using musl as libc on a 64 bit host, it sits in an infinite loop 
>> of mremap calls of ever decreasing/increasing addresses.
>>
>> I suspect something in the musl memory allocation code loops indefinitely
>> if it only sees ENOMEM and only exits when it hits EFAULT.
>>
>> According to the docs, trying to mremap outside the address space
>> can/should return EFAULT and changing this allows the build to succeed.
>>
>> There was previous discussion of this as it used to work before qemu 2.11
>> and we've carried hacks to work around it since, this appears to be a
>> better fix of the real issue?
>>
>> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org
>>
>> Index: qemu-5.2.0/linux-user/mmap.c
>> ===================================================================
>> --- qemu-5.2.0.orig/linux-user/mmap.c
>> +++ qemu-5.2.0/linux-user/mmap.c
>> @@ -727,7 +727,7 @@ abi_long target_mremap(abi_ulong old_add
>>           !guest_range_valid(new_addr, new_size)) ||
>>          ((flags & MREMAP_MAYMOVE) == 0 &&
>>           !guest_range_valid(old_addr, new_size))) {
>> -        errno = ENOMEM;
>> +        errno = EFAULT;
>>          return -1;
>>      }
> 
> Any comments on this? I believe its a valid issue that needs fixing and
> multiple distros appear to be carrying fixes in this area related to
> this.
> 
> Cheers,
> 
> Richard
> 
> 



  reply	other threads:[~2021-01-22 10:30 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-08 17:46 [RFC PATCH] linux-user/mmap: Return EFAULT for invalid addresses Richard Purdie
2021-01-22  9:37 ` Richard Purdie
2021-01-22 10:28   ` Philippe Mathieu-Daudé [this message]
2021-02-13 17:40 ` Laurent Vivier
2021-02-16 11:49   ` Richard Purdie
2021-02-16 16:21     ` Laurent Vivier
2021-02-16 19:01       ` [PATCH v2] linux-user/mmap: Return EFAULT/EINVAL " Richard Purdie
2021-02-16 19:13         ` Laurent Vivier

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