From: Al Viro <viro@zeniv.linux.org.uk>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
Peter Zijlstra <peterz@infradead.org>,
clang-built-linux@googlegroups.com,
Linus Torvalds <torvalds@linux-foundation.org>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Andy Lutomirski <luto@kernel.org>,
Sami Tolvanen <samitolvanen@google.com>,
Marco Elver <elver@google.com>, Brian Gerst <brgerst@gmail.com>,
Arnd Bergmann <arnd@arndb.de>,
Andrew Morton <akpm@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] x86: signal: move save_altstack_ex out of generic headers
Date: Sat, 4 Apr 2020 00:39:24 +0100 [thread overview]
Message-ID: <20200403233924.GM23230@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20200403231611.81444-1-ndesaulniers@google.com>
On Fri, Apr 03, 2020 at 04:16:06PM -0700, Nick Desaulniers wrote:
> In some configurations (clang+KASAN), sas_ss_reset() may emit calls to
> memset(). This is a problem for SMAP protections on x86, which should
> try to minimize calls to any function not already on short whitelist, in
> order to prevent leaking AC flags or being used as a gadget.
>
> Linus noted that unsafe_save_altstack() only has callsites in the
> arch-specific arch/x86/kernel/signal.c, and shouldn't be defined in arch
> independent headers.
>
> Split the logic of unsafe_save_altstack() into two, and move the definitions
> to arch/x86/include/asm/sigframe.h. This does less work with the SMAP
> guards down.
Just move that into signal_delivered() and that's it. SMAP or no SMAP -
doing that until the sigframe is set and we are committed to entering
the handler is wrong.
next prev parent reply other threads:[~2020-04-03 23:39 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-24 22:08 [PATCH] x86: signal: move save_altstack_ex out of generic headers Nick Desaulniers
2020-04-03 23:16 ` [PATCH v2] " Nick Desaulniers
2020-04-03 23:39 ` Al Viro [this message]
2020-04-04 16:01 ` Oleg Nesterov
2020-04-04 17:06 ` Al Viro
2020-04-04 17:31 ` Linus Torvalds
2020-04-04 17:50 ` Oleg Nesterov
2020-04-04 22:50 ` Nathan Chancellor
2020-04-13 19:12 ` Nick Desaulniers
2020-06-26 18:18 ` Nick Desaulniers
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