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SubjectRe: [PATCH 4.4 41/57] x86/fpu: Reset state for all signal restore failures
Hi!

> commit efa165504943f2128d50f63de0c02faf6dcceb0d upstream.
>
> If access_ok() or fpregs_soft_set() fails in __fpu__restore_sig() then the
> function just returns but does not clear the FPU state as it does for all
> other fatal failures.
>
> Clear the FPU state for these failures as well.

That's quite a confusing calling convention, right?

> +++ b/arch/x86/kernel/fpu/signal.c
> @@ -262,15 +262,23 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
> return 0;
> }
>
> - if (!access_ok(VERIFY_READ, buf, size))
> + if (!access_ok(VERIFY_READ, buf, size)) {
> + fpu__clear(fpu);
> return -EACCES;
> + }

This returns -errno on failure.

> fpu__activate_curr(fpu);
>
> - if (!static_cpu_has(X86_FEATURE_FPU))
> - return fpregs_soft_set(current, NULL,
> - 0, sizeof(struct user_i387_ia32_struct),
> - NULL, buf) != 0;
> + if (!static_cpu_has(X86_FEATURE_FPU)) {
> + int ret = fpregs_soft_set(current, NULL, 0,
> + sizeof(struct user_i387_ia32_struct),
> + NULL, buf);
> +
> + if (ret)
> + fpu__clear(fpu);
> +
> + return ret != 0;
> + }

And this explicitely turns negative error into 1 for maximum confusion.

I don't see the same confusion in mainline.

Best regards,
Pavel
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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