Re: [Qemu-devel] [PATCH] linux-user: correct semctl() and shmctl()

[Peter Maydell]

On 20 December 2012 20:58, Laurent Vivier <address@hidden> wrote:
> The parameter "union semun" of semctl() is not a value
> but a pointer to the value.

> @@ -3161,10 +3163,16 @@ static abi_long do_ipc(unsigned int call, int first,
>          ret = get_errno(semget(first, second, third));
>          break;
>
> -    case IPCOP_semctl:
> -        ret = do_semctl(first, second, third, (union 
> target_semun)(abi_ulong) ptr);
> +    case IPCOP_semctl: {
> +        union target_semun *target_su;
> +        if (!lock_user_struct(VERIFY_READ, target_su, ptr, 1)) {
> +            ret = -TARGET_EFAULT;
> +            break;
> +        }
> +        ret = do_semctl(first, second, third, *target_su);
> +        unlock_user_struct(target_su, ptr, 0);

Rather than doing the lock/unlock in both callers to do_semctl,
just pass do_semctl an abi_long and have it do the lock/unlock.
Rest of patch looks ok.

-- PMM