[asan] implement more strict checking for memset/etc parameters. Instead of checking the first and the last byte, we check the entire shadow region. This costs ~10 slowdown for the instrumented functions. Motivated by a nasty memset-buffer-overflow-by-140-bytes in chrome which was reported as a use-after-free or not at all

llvm-svn: 171198

1 files changed, 5 insertions, 0 deletions

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_libc.h b/compiler-rt/lib/sanitizer_common/sanitizer_libc.h
index 79794839d28..aa052c654d3 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_libc.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_libc.h
@@ -47,6 +47,11 @@ char *internal_strstr(const char *haystack, const char *needle);
 // Works only for base=10 and doesn't set errno.
 s64 internal_simple_strtoll(const char *nptr, char **endptr, int base);
 
+// Return true if all bytes in [mem, mem+size) are zero.
+// Optimized for the case when the result is true.
+bool mem_is_zero(const char *mem, uptr size);
+
+
 // Memory
 void *internal_mmap(void *addr, uptr length, int prot, int flags,
                     int fd, u64 offset);