Re: [PATCH 1/2] linux-user: Modify 'target_to_host/host_to_target_itimerspec()'

[Laurent Vivier]

Le 22/07/2020 à 13:10, Filip Bozuta a écrit :
> Functions 'target_to_host_itimerspec()' and 'host_to_target_itimerspec()'
> are used to convert values of type 'struct itimerspec' between target and
> host. This type has 'struct timespec' as its fields. That is the reason
> why this patch introduces a little modification to the converting functions
> to be implemented using already existing functions that convert 'struct 
> timespec':
> 'target_to_host_timespec()' and 'host_to_target_timespec()'. This makes the
> code of 'target_to_host_itimerspec()' and 'host_to_target_itimerspec()' more
> clean and readable.
> 
> Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
> ---
>  linux-user/syscall.c | 38 ++++++++++++--------------------------
>  1 file changed, 12 insertions(+), 26 deletions(-)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 1211e759c2..17e09c3cd3 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -1236,7 +1236,9 @@ static inline abi_long copy_to_user_timeval64(abi_ulong 
> target_tv_addr,
>      defined(TARGET_NR_nanosleep) || defined(TARGET_NR_clock_settime) || \
>      defined(TARGET_NR_utimensat) || defined(TARGET_NR_mq_timedsend) || \
>      defined(TARGET_NR_mq_timedreceive) || defined(TARGET_NR_ipc) || \
> -    defined(TARGET_NR_semop) || defined(TARGET_NR_semtimedop)
> +    defined(TARGET_NR_semop) || defined(TARGET_NR_semtimedop) || \
> +    defined(TARGET_NR_timer_settime) || \
> +    (defined(TARGET_NR_timerfd_settime) && defined(CONFIG_TIMERFD))
>  static inline abi_long target_to_host_timespec(struct timespec *host_ts,
>                                                 abi_ulong target_addr)
>  {
> @@ -6790,46 +6792,30 @@ static inline abi_long target_ftruncate64(void 
> *cpu_env, abi_long arg1,
>  
>  #if defined(TARGET_NR_timer_settime) || \
>      (defined(TARGET_NR_timerfd_settime) && defined(CONFIG_TIMERFD))
> -static inline abi_long target_to_host_itimerspec(struct itimerspec 
> *host_itspec,
> +static inline abi_long target_to_host_itimerspec(struct itimerspec *host_its,
>                                                   abi_ulong target_addr)
>  {
> -    struct target_itimerspec *target_itspec;
> -
> -    if (!lock_user_struct(VERIFY_READ, target_itspec, target_addr, 1)) {
> +    if (target_to_host_timespec(&host_its->it_interval, target_addr) ||
> +        target_to_host_timespec(&host_its->it_value, target_addr +
> +                                sizeof(struct target_timespec))) {

The "+ sizeof(struct target_timespec)" ignores possible type alignment
in the structure.

I think it is safer to use "+ offsetof(struct target_timespec,
it_interval)" for the first one and "+ offsetof(struct target_timespec,
it_value)" for the second one.

Thanks,
Laurent