FORTIFY_SOURCE: strlen check.
This test is designed to detect code such as:
int main() {
char buf[10];
memcpy(buf, "1234567890", sizeof(buf));
size_t len = strlen(buf); // segfault here with _FORTIFY_SOURCE
printf("%d\n", len);
return 0;
}
or anytime strlen reads beyond an object boundary. This should
help address memory leakage vulnerabilities and make other
unrelated vulnerabilities harder to exploit.
Change-Id: I354b425be7bef4713c85f6bab0e9738445e00182
diff --git a/libc/include/string.h b/libc/include/string.h
index 269f7ac..842aa39 100644
--- a/libc/include/string.h
+++ b/libc/include/string.h
@@ -216,6 +216,19 @@
return __strlcat_chk(dest, src, size, bos);
}
+__purefunc extern size_t __strlen_real(const char *)
+ __asm__(__USER_LABEL_PREFIX__ "strlen");
+extern size_t __strlen_chk(const char *, size_t);
+
+__BIONIC_FORTIFY_INLINE
+size_t strlen(const char *s) {
+ size_t bos = __builtin_object_size(s, 0);
+ if (bos == (size_t) -1) {
+ return __strlen_real(s);
+ }
+ return __strlen_chk(s, bos);
+}
+
#endif /* defined(__BIONIC_FORTIFY_INLINE) */