[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH v2] linux-user/mmap.c: Avoid choosing NULL as st
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH v2] linux-user/mmap.c: Avoid choosing NULL as start address |
Date: |
Mon, 8 Jan 2018 12:28:05 -0800 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 |
On 01/06/2018 05:01 PM, Maximilian Riemensberger wrote:
> mmap() is required by the linux kernel ABI and POSIX to return a
> non-NULL address when the implementation chooses a start address for the
> mapping.
>
> The current implementation of mmap_find_vma_reserved() can return NULL
> as start address of a mapping which leads to subsequent crashes inside
> the guests glibc, e.g. output of qemu-arm-static --strace executing a
> test binary stx_test:
>
> 1879
> mmap2(NULL,8388608,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANONYMOUS|0x20000,-1,0)
> = 0x00000000
> 1879 write(2,0xf6fd39d0,79) stx_test: allocatestack.c:514:
> allocate_stack: Assertion `mem != NULL' failed.
>
> This patch fixes mmap_find_vma_reserved() by skipping NULL as start
> address while searching for a suitable mapping start address.
>
> CC: Riku Voipio <address@hidden>
> CC: Laurent Vivier <address@hidden>
> CC: Peter Maydell <address@hidden>
> Signed-off-by: Maximilian Riemensberger <address@hidden>
> ---
> Changes since v1:
> - Applied feedback from Laurent Vivier
Reviewed-by: Richard Henderson <address@hidden>
r~