From: Kees Cook <keescook@chromium.org>
To: Wei Liu <wei.liu@kernel.org>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Dexuan Cui <decui@microsoft.com>,
linux-hyperv@vger.kernel.org,
Nathan Chancellor <nathan@kernel.org>,
linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH] Drivers: hv: vmbus: Split memcpy of flex-array
Date: Tue, 27 Sep 2022 14:23:59 -0700 [thread overview]
Message-ID: <202209271423.EA345AD@keescook> (raw)
In-Reply-To: <Yy7dJP4p0FMQfPl5@liuwe-devbox-debian-v2>
On Sat, Sep 24, 2022 at 10:34:12AM +0000, Wei Liu wrote:
> Hi Kees
>
> On Fri, Sep 23, 2022 at 09:22:55PM -0700, Kees Cook wrote:
> > On Fri, Sep 23, 2022 at 10:42:38PM -0500, Gustavo A. R. Silva wrote:
> > > On Fri, Sep 23, 2022 at 08:07:41PM -0700, Kees Cook wrote:
> > > > To work around a misbehavior of the compiler's ability to see into
> > > > composite flexible array structs (as detailed in the coming memcpy()
> > > > hardening series[1]), split the memcpy() of the header and the payload
> > > > so no false positive run-time overflow warning will be generated. As it
> > > > turns out, this appears to actually reduce the text size:
> >
> > Er, actually, I can't read/math. ;) It _does_ grow the text size. (That's
> > 2_3_ not 22 at the start of the text size...) On examination, it appears
> > to unroll the already inlined memcpy further.
>
> Can you provide an updated commit message? No need to resend.
Since I got more testing from Nathan (and the original warning message),
I figured a full v2 respin would easier. Now sent. :) Thanks!
-Kees
--
Kees Cook
next prev parent reply other threads:[~2022-09-27 21:24 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-24 3:07 [PATCH] Drivers: hv: vmbus: Split memcpy of flex-array Kees Cook
2022-09-24 3:42 ` Gustavo A. R. Silva
2022-09-24 4:22 ` Kees Cook
2022-09-24 10:34 ` Wei Liu
2022-09-27 21:23 ` Kees Cook [this message]
2022-09-27 20:46 ` Nathan Chancellor
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