[compiler-rt] r300889 - [asan] Optimize strchr for strict_string_checks=false
Vitaly Buka via llvm-commits
llvm-commits at lists.llvm.org
Thu Apr 20 18:30:30 PDT 2017
Thanks,
Maybe r300939 would fix.
On Thu, Apr 20, 2017 at 6:20 PM Ahmed Bougacha <ahmed.bougacha at gmail.com>
wrote:
> Hey Vitaly,
>
> I saw your fixes in r300906 and r300935, but this fails differently
> for me on Darwin:
>
>
> ASAN:DEADLYSIGNAL
> =================================================================
> ==52312==ERROR: AddressSanitizer: BUS on unknown address
> 0x00010affd000 (pc 0x7fff999a7168 bp 0x7fff57e31270 sp 0x7fff57e31270
> T0)
> #0 0x7fff999a7167 in strlen (libsystem_c.dylib:x86_64+0x1167)
> #1 0x107dee5bb in wrap_strchr sanitizer_common_interceptors.inc:578
> #2 0x107dceaa5 in main strchr.c:29
> #3 0x7fff970345ac in start (libdyld.dylib:x86_64+0x35ac)
>
> ==52312==Register values:
> ....
> AddressSanitizer can not provide additional info.
> SUMMARY: AddressSanitizer: BUS (libsystem_c.dylib:x86_64+0x1167) in strlen
> ==52312==ABORTING
>
>
> Does that ring a bell?
>
> Thanks!
> -Ahmed
>
>
> On Thu, Apr 20, 2017 at 1:59 PM, Vitaly Buka via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
> > Author: vitalybuka
> > Date: Thu Apr 20 15:59:37 2017
> > New Revision: 300889
> >
> > URL: http://llvm.org/viewvc/llvm-project?rev=300889&view=rev
> > Log:
> > [asan] Optimize strchr for strict_string_checks=false
> >
> > Summary:
> > strchr interceptor does not need to call strlen if strict_string_checks
> is not
> > enabled. Unnecessary strlen calls affect python parser performance.
> >
> > Reviewers: eugenis, kcc
> >
> > Subscribers: llvm-commits, kubamracek
> >
> > Differential Revision: https://reviews.llvm.org/D32264
> >
> > Added:
> > compiler-rt/trunk/test/asan/TestCases/Posix/strchr.c
> > Modified:
> >
> compiler-rt/trunk/lib/sanitizer_common/sanitizer_common_interceptors.inc
> >
> > Modified:
> compiler-rt/trunk/lib/sanitizer_common/sanitizer_common_interceptors.inc
> > URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_common_interceptors.inc?rev=300889&r1=300888&r2=300889&view=diff
> >
> ==============================================================================
> > ---
> compiler-rt/trunk/lib/sanitizer_common/sanitizer_common_interceptors.inc
> (original)
> > +++
> compiler-rt/trunk/lib/sanitizer_common/sanitizer_common_interceptors.inc
> Thu Apr 20 15:59:37 2017
> > @@ -139,12 +139,9 @@ bool PlatformHasDifferentMemcpyAndMemmov
> > #define COMMON_INTERCEPTOR_NOTHING_IS_INITIALIZED (0)
> > #endif
> >
> > -#define COMMON_INTERCEPTOR_READ_STRING_OF_LEN(ctx, s, len, n) \
> > - COMMON_INTERCEPTOR_READ_RANGE((ctx), (s), \
> > - common_flags()->strict_string_checks ? (len) + 1 : (n) )
> > -
> > #define COMMON_INTERCEPTOR_READ_STRING(ctx, s, n) \
> > - COMMON_INTERCEPTOR_READ_STRING_OF_LEN((ctx), (s), REAL(strlen)(s),
> (n))
> > + COMMON_INTERCEPTOR_READ_RANGE((ctx), (s), \
> > + common_flags()->strict_string_checks ? (REAL(strlen)(s)) + 1 :
> (n) )
> >
> > #ifndef COMMON_INTERCEPTOR_ON_DLOPEN
> > #define COMMON_INTERCEPTOR_ON_DLOPEN(filename, flag) \
> > @@ -450,8 +447,7 @@ static inline void StrstrCheck(void *ctx
> > const char *s2) {
> > uptr len1 = REAL(strlen)(s1);
> > uptr len2 = REAL(strlen)(s2);
> > - COMMON_INTERCEPTOR_READ_STRING_OF_LEN(ctx, s1, len1,
> > - r ? r - s1 + len2 : len1 + 1);
> > + COMMON_INTERCEPTOR_READ_STRING(ctx, s1, r ? r - s1 + len2 : len1 +
> 1);
> > COMMON_INTERCEPTOR_READ_RANGE(ctx, s2, len2 + 1);
> > }
> > #endif
> > @@ -577,10 +573,11 @@ INTERCEPTOR(char*, strchr, const char *s
> > return internal_strchr(s, c);
> > COMMON_INTERCEPTOR_ENTER(ctx, strchr, s, c);
> > char *result = REAL(strchr)(s, c);
> > - uptr len = internal_strlen(s);
> > - uptr n = result ? result - s + 1 : len + 1;
> > - if (common_flags()->intercept_strchr)
> > - COMMON_INTERCEPTOR_READ_STRING_OF_LEN(ctx, s, len, n);
> > + if (common_flags()->intercept_strchr) {
> > + // Keep strlen as macro argument, as macro may ignore it.
> > + COMMON_INTERCEPTOR_READ_STRING(ctx, s,
> > + (result ? result - s : REAL(strlen)(s)) + 1);
> > + }
> > return result;
> > }
> > #define INIT_STRCHR COMMON_INTERCEPT_FUNCTION(strchr)
> > @@ -609,9 +606,8 @@ INTERCEPTOR(char*, strrchr, const char *
> > if (COMMON_INTERCEPTOR_NOTHING_IS_INITIALIZED)
> > return internal_strrchr(s, c);
> > COMMON_INTERCEPTOR_ENTER(ctx, strrchr, s, c);
> > - uptr len = internal_strlen(s);
> > if (common_flags()->intercept_strchr)
> > - COMMON_INTERCEPTOR_READ_STRING_OF_LEN(ctx, s, len, len + 1);
> > + COMMON_INTERCEPTOR_READ_RANGE(ctx, s, REAL(strlen)(s) + 1);
> > return REAL(strrchr)(s, c);
> > }
> > #define INIT_STRRCHR COMMON_INTERCEPT_FUNCTION(strrchr)
> >
> > Added: compiler-rt/trunk/test/asan/TestCases/Posix/strchr.c
> > URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/asan/TestCases/Posix/strchr.c?rev=300889&view=auto
> >
> ==============================================================================
> > --- compiler-rt/trunk/test/asan/TestCases/Posix/strchr.c (added)
> > +++ compiler-rt/trunk/test/asan/TestCases/Posix/strchr.c Thu Apr 20
> 15:59:37 2017
> > @@ -0,0 +1,36 @@
> > +// Test strchr for strict_string_checks=false does not look beyond
> necessary
> > +// char.
> > +// RUN: %clang_asan %s -o %t
> > +// RUN: %env_asan_opts=strict_string_checks=false %run %t 2>&1
> > +// RUN: %env_asan_opts=strict_string_checks=true not %run %t 2>&1 |
> FileCheck %s
> > +
> > +#include <assert.h>
> > +#include <stdint.h>
> > +#include <stdlib.h>
> > +#include <string.h>
> > +#include <sys/mman.h>
> > +#include <unistd.h>
> > +
> > +int main(int argc, char **argv) {
> > + size_t page_size = sysconf(_SC_PAGE_SIZE);
> > + size_t size = 2 * page_size;
> > + char *s = (char *)mmap(0, size, PROT_READ | PROT_WRITE,
> > + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
> > + assert(s);
> > + assert(((uintptr_t)s & (page_size - 1)) == 0);
> > + memset(s, 'o', size);
> > + s[size - 1] = 0;
> > +
> > + char *p = s + page_size - 1;
> > + *p = 'x';
> > +
> > + if (mprotect(p + 1, 1, PROT_NONE))
> > + return 1;
> > + char *r = strchr(s, 'x');
> > + // CHECK: AddressSanitizer: SEGV on unknown address
> > + // CHECK: The signal is caused by a READ memory access
> > + // CHECK: strchr.c:[[@LINE-3]]
> > + assert(r == p);
> > +
> > + return 0;
> > +}
> >
> >
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>
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