Re: [Qemu-devel] [PATCH v1 for 3.0 1/2] linux-user/mmap.c: handle len = 0 maps correctly

[Laurent Vivier]

Le 26/07/2018 à 15:29, Alex Bennée a écrit :
> I've slightly re-organised the check to more closely match the
> sequence that the kernel uses in do_mmap().
> 
> Signed-off-by: Alex Bennée <address@hidden>
> Cc: umarcor <address@hidden>
> ---
>  linux-user/mmap.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/linux-user/mmap.c b/linux-user/mmap.c
> index d0c50e4888..3ef69fa2d0 100644
> --- a/linux-user/mmap.c
> +++ b/linux-user/mmap.c
> @@ -391,14 +391,22 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, 
> int prot,
>      }
>  #endif
>  
> -    if (offset & ~TARGET_PAGE_MASK) {
> +    if (!len) {
>          errno = EINVAL;
>          goto fail;
>      }
>  
>      len = TARGET_PAGE_ALIGN(len);
> -    if (len == 0)
> -        goto the_end;
> +    if (!len) {
> +        errno = EINVAL;
> +        goto fail;
> +    }

Why do you check twice len?
TARGET_PAGE_ALIGN() rounds up the value, so if it was not 0, it cannot
be now.

Thanks,
Laurent