Re: [PATCH v2 1/2] linux-user: rt_sigprocmask, check read perms first

[Laurent Vivier <laurent@vivier.eu>]

Le 26/01/2022 à 18:58, Patrick Venture a écrit :
> From: Shu-Chun Weng <scw@google.com>
> 
> Linux kernel does it this way (checks read permission before validating `how`)
> and the latest version of ABSL's `AddressIsReadable()` depends on this
> behavior.
> 
> c.f.  https://github.com/torvalds/linux/blob/9539ba4308ad5bdca6cb41c7b73cbb9f796dcdd7/kernel/signal.c#L3147
> Reviewed-by: Patrick Venture <venture@google.com>
> Signed-off-by: Shu-Chun Weng <scw@google.com>

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

but you must resend the patch: you are not the author, but you have to add your Signed-off-by.
(and now you can add my reviewed-by)

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/SubmittingPatches?id=f6f94e2ab1b33f0082ac22d71f66385a60d8157f#n296

Thanks,
Laurent

> ---
>   linux-user/syscall.c | 12 +++++++-----
>   1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 5950222a77..34bd819e38 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -9508,6 +9508,13 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
>               }
>   
>               if (arg2) {
> +                p = lock_user(VERIFY_READ, arg2, sizeof(target_sigset_t), 1);
> +                if (!p) {
> +                    return -TARGET_EFAULT;
> +                }
> +                target_to_host_sigset(&set, p);
> +                unlock_user(p, arg2, 0);
> +                set_ptr = &set;
>                   switch(how) {
>                   case TARGET_SIG_BLOCK:
>                       how = SIG_BLOCK;
> @@ -9521,11 +9528,6 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
>                   default:
>                       return -TARGET_EINVAL;
>                   }
> -                if (!(p = lock_user(VERIFY_READ, arg2, sizeof(target_sigset_t), 1)))
> -                    return -TARGET_EFAULT;
> -                target_to_host_sigset(&set, p);
> -                unlock_user(p, arg2, 0);
> -                set_ptr = &set;
>               } else {
>                   how = 0;
>                   set_ptr = NULL;