Re: [Qemu-devel] [PATCH 10/11] linux-user/syscall: verify recvfrom(addr) is user-writable

[Laurent Vivier]

Le 24/01/2018 à 14:01, Philippe Mathieu-Daudé a écrit :
> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
> ---
>  linux-user/syscall.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 11c9116c4a..b6b9beca5b 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -4040,6 +4040,11 @@ static abi_long do_recvfrom(int fd, abi_ulong msg, 
> size_t len, int flags,
>              ret = -TARGET_EINVAL;
>              goto fail;
>          }
> +        if (!access_ok(VERIFY_WRITE, target_addr, addrlen)) {
> +            ret = -TARGET_EFAULT;
> +            goto fail;
> +        }
> +
>          addr = alloca(addrlen);
>          ret = get_errno(safe_recvfrom(fd, host_msg, len, flags,
>                                        addr, &addrlen));
> 

Even if host_to_target_sockaddr() will do the check before copying data
to the target, I think it is good to check this before reading the data, so:

Reviewed-by: Laurent Vivier <address@hidden>

Thanks,
Laurent