Re: [PATCH] linux-user: Fix syscall rt_sigtimedwait() implementation

[Laurent Vivier]

Le 24/07/2020 à 20:16, Filip Bozuta a écrit :
> Implementation of 'rt_sigtimedwait()' in 'syscall.c' uses the
> function 'target_to_host_timespec()' to transfer the value of
> 'struct timespec' from target to host. However, the implementation
> doesn't check whether this conversion succeeds and thus can cause
> an unaproppriate error instead of the 'EFAULT (Bad address)' which
> is supposed to be set if the conversion from target to host fails.
> 
> This was confirmed with the LTP test for rt_sigtimedwait:
> "/testcases/kernel/syscalls/rt_sigtimedwait/rt_sigtimedwait01.c"
> which causes an unapropriate error in test case "test_bad_adress3"
> which is run with a bad adress for the 'struct timespec' argument:
> 
> FAIL: test_bad_address3 (349): Unexpected failure: EAGAIN/EWOULDBLOCK (11)
> 
> The test fails with an unexptected errno 'EAGAIN/EWOULDBLOCK' instead
> of the expected EFAULT.
> 
> After the changes from this patch, the test case is executed successfully
> along with the other LTP test cases for 'rt_sigtimedwait()':
> 
> PASS: test_bad_address3 (349): Test passed
> 
> Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
> ---
>  linux-user/syscall.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 1211e759c2..72735682cb 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -8868,7 +8868,9 @@ static abi_long do_syscall1(void *cpu_env, int num, 
> abi_long arg1,
>              unlock_user(p, arg1, 0);
>              if (arg3) {
>                  puts = &uts;
> -                target_to_host_timespec(puts, arg3);
> +                if (target_to_host_timespec(puts, arg3)) {
> +                    return -TARGET_EFAULT;
> +                }
>              } else {
>                  puts = NULL;
>              }
> 

Reviewed-by: Laurent Vivier <laurent@vivier.eu>