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[libc] use vars in string to num fuzz targets

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The string to integer and string to float standalone fuzz targets just
ran the functions and didn't do anything with the output. This was
intentional, since they are intended to be used with sanitizers to
detect buffer overflow bugs. Not using the variables was causing compile
warnings, so this patch adds trivial checks to use the variables.

Reviewed By: sivachandra, lntue

Differential Revision: https://reviews.llvm.org/D144208
This commit is contained in:
Michael Jones 2023-02-16 11:23:44 -08:00
parent 387452ec59
commit 62e7bdd22a
2 changed files with 25 additions and 3 deletions
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18
libc/fuzzing/stdlib/strtofloat_fuzz.cpp
View File

@ -13,6 +13,7 @@
#include "src/stdlib/strtod.h"
#include "src/stdlib/strtof.h"
#include "src/stdlib/strtold.h"
#include <math.h>
#include <stddef.h>
#include <stdint.h>
@ -30,10 +31,10 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
char *out_ptr = nullptr;
// This fuzzer only checks that the alrogithms didn't read beyond the end of
// This fuzzer only checks that the algorithms didn't read beyond the end of
// the string in container. Combined with sanitizers, this will check that the
// code is not reading memory beyond what's expected. This test does not make
// any attempt to check correctness of the result.
// code is not reading memory beyond what's expected. This test does not
// effectively check the correctness of the result.
auto volatile atof_output = __llvm_libc::atof(str_ptr);
auto volatile strtof_output = __llvm_libc::strtof(str_ptr, &out_ptr);
if (str_ptr + size < out_ptr)
@ -45,6 +46,17 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
if (str_ptr + size < out_ptr)
__builtin_trap();
// If any of the outputs are NaN
if (isnan(atof_output) || isnan(strtof_output) || isnan(strtod_output) ||
isnan(strtold_output)) {
// Then all the outputs should be NaN.
// This is a trivial check meant to silence the "unused variable" warnings.
if (!isnan(atof_output) || !isnan(strtof_output) || !isnan(strtod_output) ||
!isnan(strtold_output)) {
__builtin_trap();
}
}
delete[] container;
return 0;
}

10
libc/fuzzing/stdlib/strtointeger_fuzz.cpp
View File

@ -65,6 +65,16 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
if (str_ptr + container_size - 1 < out_ptr)
__builtin_trap();
// If atoi is non-zero and the base is at least 10
if (atoi_output != 0 && base >= 10) {
// Then all of the other functions should output non-zero values as well.
// This is a trivial check meant to silence the "unused variable" warnings.
if (atol_output == 0 || atoll_output == 0 || strtol_output == 0 ||
strtoll_output == 0 || strtoul_output == 0 || strtoull_output == 0) {
__builtin_trap();
}
}
delete[] container;
return 0;
}