Le 07/01/2018 à 02:01, Maximilian Riemensberger a écrit :
> 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 <riku.voi...@iki.fi>
> CC: Laurent Vivier <laur...@vivier.eu>
> CC: Peter Maydell <peter.mayd...@linaro.org>
> Signed-off-by: Maximilian Riemensberger <riemensber...@cadami.net>
> ---
> Changes since v1:
> - Applied feedback from Laurent Vivier
>
> linux-user/mmap.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/linux-user/mmap.c b/linux-user/mmap.c
> index 4888f53..0fbfd6d 100644
> --- a/linux-user/mmap.c
> +++ b/linux-user/mmap.c
> @@ -234,7 +234,7 @@ static abi_ulong mmap_find_vma_reserved(abi_ulong start,
> abi_ulong size)
> if (prot) {
> end_addr = addr;
> }
> - if (addr + size == end_addr) {
> + if (addr && addr + size == end_addr) {
> break;
> }
> addr -= qemu_host_page_size;
>
Applied to my linux-user branch.
Thanks,
Laurent
