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Re: [Qemu-devel] [PATCH] linux-user: fix mq_getsetattr implementation


From: Laurent Vivier
Subject: Re: [Qemu-devel] [PATCH] linux-user: fix mq_getsetattr implementation
Date: Sat, 31 Mar 2018 18:57:31 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0

Le 31/03/2018 à 18:23, Max Filippov a écrit :
> mq_getsetattr implementation does not set errno correctly in case of
> error. Also in the presence of both 2nd and 3rd arguments it calls both
> mq_getattr and mq_setattr, whereas only the latter call would suffice.
> 
> Don't call mq_getattr in the presence of the 3rd argument. Use get_errno
> to set errno value.
> 
> This fixes test rt/tst-mqueue2 from the glibc testsuite.
> 
> Cc: Lionel Landwerlin <address@hidden>
> Cc: Kirill A. Shutemov <address@hidden>
> Cc: Riku Voipio <address@hidden>
> Cc: Aurelien Jarno <address@hidden>
> Cc: Laurent Vivier <address@hidden>
> Signed-off-by: Max Filippov <address@hidden>
> ---
>  linux-user/syscall.c | 13 +++++++------
>  1 file changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 18ea79140f16..8b364551c311 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -12092,15 +12092,16 @@ abi_long do_syscall(void *cpu_env, int num, 
> abi_long arg1,
>          {
>              struct mq_attr posix_mq_attr_in, posix_mq_attr_out;
>              ret = 0;

you can remove this line

> -            if (arg3 != 0) {
> -                ret = mq_getattr(arg1, &posix_mq_attr_out);
> -                copy_to_user_mq_attr(arg3, &posix_mq_attr_out);
> -            }
>              if (arg2 != 0) {
>                  copy_from_user_mq_attr(&posix_mq_attr_in, arg2);
> -                ret |= mq_setattr(arg1, &posix_mq_attr_in, 
> &posix_mq_attr_out);
> +                ret = mq_setattr(arg1, &posix_mq_attr_in, 
> &posix_mq_attr_out);

you can call get_errno(mq_setattr(..)) here...

> +            } else if (arg3 != 0) {
> +                ret = mq_getattr(arg1, &posix_mq_attr_out);

and get_errno(q_getattr(..)) here.

>              }
> -
> +            if (arg3 != 0) {

you should also check ret < 0 before copying to arg3

> +                copy_to_user_mq_attr(arg3, &posix_mq_attr_out);
> +            }
> +            ret = get_errno(ret);

you can remove this line if you call get_errno() directly before.


>          }
>          break;
>  #endif
> 

Thanks,
Laurent



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