Messages in this thread Patch in this message | | | Subject | Re: Re: [PATCH v2] arm64: kasan: add interceptors for strcmp/strncmp functions | From | Kyeongdon Kim <> | Date | Wed, 5 Sep 2018 16:44:54 +0900 |
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On 2018-09-05 오전 1:24, Andrey Ryabinin wrote: > > > On 09/04/2018 01:10 PM, Andrey Ryabinin wrote: > > > > > > On 09/04/2018 09:59 AM, Kyeongdon Kim wrote: > > > >>>> +#undef strncmp > >>>> +int strncmp(const char *cs, const char *ct, size_t len) > >>>> +{ > >>>> + check_memory_region((unsigned long)cs, len, false, _RET_IP_); > >>>> + check_memory_region((unsigned long)ct, len, false, _RET_IP_); > >>> > >>> This will cause false positives. Both 'cs', and 'ct' could be less > than len bytes. > >>> > >>> There is no need in these interceptors, just use the C > implementations from lib/string.c > >>> like you did in your first patch. > >>> The only thing that was wrong in the first patch is that assembly > implementations > >>> were compiled out instead of being declared week. > >>> > >> Well, at first I thought so.. > >> I would remove diff code in /mm/kasan/kasan.c then use C > implementations in lib/string.c > >> w/ assem implementations as weak : > >> > >> diff --git a/lib/string.c b/lib/string.c > >> index 2c0900a..a18b18f 100644 > >> --- a/lib/string.c > >> +++ b/lib/string.c > >> @@ -312,7 +312,7 @@ size_t strlcat(char *dest, const char *src, > size_t count) > >> EXPORT_SYMBOL(strlcat); > >> #endif > >> > >> -#ifndef __HAVE_ARCH_STRCMP > >> +#if (defined(CONFIG_ARM64) && defined(CONFIG_KASAN)) || > !defined(__HAVE_ARCH_STRCMP) > > > > No. What part of "like you did in your first patch" is unclear to you? > > Just to be absolutely clear, I meant #ifdef out __HAVE_ARCH_* defines > like it has been done in this patch > http://lkml.kernel.org/r/<1534233322-106271-1-git-send-email-kyeongdon.kim@lge.com> > I understood what you're saying, but I might think the wrong patch.
So, thinking about the other way as below: can pick up assem variant or c one, declare them as weak. --- diff --git a/arch/arm64/include/asm/string.h b/arch/arm64/include/asm/string.h index dd95d33..53a2ae0 100644 --- a/arch/arm64/include/asm/string.h +++ b/arch/arm64/include/asm/string.h @@ -22,11 +22,22 @@ extern char *strrchr(const char *, int c); #define __HAVE_ARCH_STRCHR extern char *strchr(const char *, int c);
+#ifdef CONFIG_KASAN +extern int __strcmp(const char *, const char *); +extern int __strncmp(const char *, const char *, __kernel_size_t); + +#ifndef __SANITIZE_ADDRESS__ +#define strcmp(cs, ct) __strcmp(cs, ct) +#define strncmp(cs, ct, n) __strncmp(cs, ct, n) +#endif + +#else #define __HAVE_ARCH_STRCMP extern int strcmp(const char *, const char *);
#define __HAVE_ARCH_STRNCMP extern int strncmp(const char *, const char *, __kernel_size_t); +#endif
#define __HAVE_ARCH_STRLEN extern __kernel_size_t strlen(const char *); diff --git a/arch/arm64/kernel/arm64ksyms.c b/arch/arm64/kernel/arm64ksyms.c index d894a20..9aeffd5 100644 --- a/arch/arm64/kernel/arm64ksyms.c +++ b/arch/arm64/kernel/arm64ksyms.c @@ -50,6 +50,10 @@ EXPORT_SYMBOL(strcmp); EXPORT_SYMBOL(strncmp); EXPORT_SYMBOL(strlen); EXPORT_SYMBOL(strnlen); +#ifdef CONFIG_KASAN +EXPORT_SYMBOL(__strcmp); +EXPORT_SYMBOL(__strncmp); +#endif EXPORT_SYMBOL(memset); EXPORT_SYMBOL(memcpy); EXPORT_SYMBOL(memmove); diff --git a/arch/arm64/kernel/image.h b/arch/arm64/kernel/image.h index a820ed0..5ef7a57 100644 --- a/arch/arm64/kernel/image.h +++ b/arch/arm64/kernel/image.h @@ -110,6 +110,8 @@ __efistub___flush_dcache_area = KALLSYMS_HIDE(__pi___flush_dcache_area); __efistub___memcpy = KALLSYMS_HIDE(__pi_memcpy); __efistub___memmove = KALLSYMS_HIDE(__pi_memmove); __efistub___memset = KALLSYMS_HIDE(__pi_memset); +__efistub___strcmp = KALLSYMS_HIDE(__pi_strcmp); +__efistub___strncmp = KALLSYMS_HIDE(__pi_strncmp); #endif
__efistub__text = KALLSYMS_HIDE(_text); diff --git a/arch/arm64/lib/strcmp.S b/arch/arm64/lib/strcmp.S index 471fe61..0dffef7 100644 --- a/arch/arm64/lib/strcmp.S +++ b/arch/arm64/lib/strcmp.S @@ -60,6 +60,8 @@ tmp3 .req x9 zeroones .req x10 pos .req x11
+.weak strcmp +ENTRY(__strcmp) ENTRY(strcmp) eor tmp1, src1, src2 mov zeroones, #REP8_01 @@ -232,3 +234,4 @@ CPU_BE( orr syndrome, diff, has_nul ) sub result, data1, data2, lsr #56 ret ENDPIPROC(strcmp) +ENDPROC(__strcmp) diff --git a/arch/arm64/lib/strncmp.S b/arch/arm64/lib/strncmp.S index e267044..b2648c7 100644 --- a/arch/arm64/lib/strncmp.S +++ b/arch/arm64/lib/strncmp.S @@ -64,6 +64,8 @@ limit_wd .req x13 mask .req x14 endloop .req x15
+.weak strncmp +ENTRY(__strncmp) ENTRY(strncmp) cbz limit, .Lret0 eor tmp1, src1, src2 @@ -308,3 +310,4 @@ CPU_BE( orr syndrome, diff, has_nul ) mov result, #0 ret ENDPIPROC(strncmp) +ENDPROC(__strncmp) -- Could you review this diff?
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