Re: [Qemu-devel] [PATCH v2 7/7] linux-user: Fix mq_open

[Peter Maydell]

On 24 November 2016 at 16:08, Lena Djokic <address@hidden> wrote:
> If fourth argument is NULL it should be passed without
> using lock_user function which would, in that case, return
> EFAULT, and system call supports passing NULL as fourth argument.
>
> Signed-off-by: Lena Djokic <address@hidden>
> ---
>  linux-user/syscall.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 3faf4f0..dad03e9 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -11694,17 +11694,22 @@ abi_long do_syscall(void *cpu_env, int num, 
> abi_long arg1,
>      case TARGET_NR_mq_open:
>          {
>              struct mq_attr posix_mq_attr;
> +            struct mq_attr *pposix_mq_attr;
>              int host_flags;
>
>              host_flags = target_to_host_bitmask(arg2, fcntl_flags_tbl);
> -            if (copy_from_user_mq_attr(&posix_mq_attr, arg4) != 0) {
> -                goto efault;
> +            pposix_mq_attr = NULL;
> +            if (arg4) {
> +                if (copy_from_user_mq_attr(&posix_mq_attr, arg4) != 0) {
> +                    goto efault;
> +                }
> +                pposix_mq_attr = &posix_mq_attr;
>              }
>              p = lock_user_string(arg1 - 1);
>              if (!p) {
>                  goto efault;
>              }
> -            ret = get_errno(mq_open(p, host_flags, arg3, &posix_mq_attr));
> +            ret = get_errno(mq_open(p, host_flags, arg3, pposix_mq_attr));
>              unlock_user (p, arg1, 0);
>          }
>          break;
> --
> 2.7.4

Reviewed-by: Peter Maydell <address@hidden>

thanks
-- PMM