lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Wed, 20 Mar 2024 19:39:49 +0900
From: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To: Alexander Potapenko <glider@...gle.com>
Cc: akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, kasan-dev@...glegroups.com, tglx@...utronix.de,
        x86@...nel.org, Linus Torvalds <torvalds@...ux-foundation.org>,
        Dmitry Vyukov <dvyukov@...gle.com>, Marco Elver <elver@...gle.com>
Subject: Re: [PATCH v1 3/3] x86: call instrumentation hooks from copy_mc.c

On 2024/03/20 18:29, Alexander Potapenko wrote:
> But for KASAN/KCSAN we can afford more aggressive checks.
> First, if we postpone them after the actual memory accesses happen,
> the kernel may panic on the invalid access without a decent error
> report.
> Second, even if in a particular case only `len-ret` bytes were copied,
> the caller probably expected both `src` and `dst` to have `len`
> addressable bytes.
> Checking for the whole length in this case is more likely to detect a
> real error than produce a false positive.

KASAN/KCSAN care about whether the requested address range is accessible but
do not care about whether the requested address range was actually accessed?

By the way, we have the same problem for copy_page() and I was thinking about
https://lkml.kernel.org/r/1a817eb5-7cd8-44d6-b409-b3bc3f377cb9@I-love.SAKURA.ne.jp .
But given that instrument_memcpy_{before,after} are added,
how do we want to use instrument_memcpy_{before,after} for copy_page() ?
Should we rename assembly version of copy_page() so that we don't need to use
tricky wrapping like below?

diff --git a/arch/x86/include/asm/page_64.h b/arch/x86/include/asm/page_64.h
index cc6b8e087192..b9b794656880 100644
--- a/arch/x86/include/asm/page_64.h
+++ b/arch/x86/include/asm/page_64.h
@@ -9,6 +9,7 @@
 #include <asm/alternative.h>
 
 #include <linux/kmsan-checks.h>
+#include <linux/instrumented.h>
 
 /* duplicated to the one in bootmem.h */
 extern unsigned long max_pfn;
@@ -59,6 +60,13 @@ static inline void clear_page(void *page)
 }
 
 void copy_page(void *to, void *from);
+#define copy_page(to, from) do {				\
+	void *_to = (to);					\
+	void *_from = (from);					\
+	instrument_memcpy_before(_to, _from, PAGE_SIZE);	\
+	copy_page(_to, _from);					\
+	instrument_memcpy_after(_to, _from, PAGE_SIZE, 0);	\
+} while (0)
 
 #ifdef CONFIG_X86_5LEVEL
 /*



Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ