linux-kernel - Re: [PATCH v6 3/9] x86: vdso: Expose sigreturn address on vdso to the kernel

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Message-ID: <202009221240.D7B051D3@keescook>
Date:   Tue, 22 Sep 2020 12:40:42 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Gabriel Krisman Bertazi <krisman@...labora.com>
Cc:     luto@...nel.org, tglx@...utronix.de, x86@...nel.org,
        linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
        willy@...radead.org, linux-kselftest@...r.kernel.org,
        shuah@...nel.org, kernel@...labora.com
Subject: Re: [PATCH v6 3/9] x86: vdso: Expose sigreturn address on vdso to
 the kernel

On Fri, Sep 04, 2020 at 04:31:41PM -0400, Gabriel Krisman Bertazi wrote:
> Syscall user redirection requires the signal trampoline code to not be
> captured, in order to support returning with a locked selector while
> avoiding recursion back into the signal handler.  For ia-32, which has
> the trampoline in the vDSO, expose the entry points to the kernel, such
> that it can avoid dispatching syscalls from that region to userspace.
> 
> Changes since V1
>   - Change return address to bool (Andy)
> 
> Suggested-by: Andy Lutomirski <luto@...nel.org>
> Acked-by: Andy Lutomirski <luto@...nel.org>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@...labora.com>

Look good to me; would anything else benefit from this information?

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook