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[dfsan] Fix a bug in strcasecmp() and strncasecmp(): Compare the lowercase versions of the characters when choosing a return value. 

Summary:
Resolves this bug:

  https://bugs.llvm.org/show_bug.cgi?id=38369

Reviewers: morehouse, pcc

Reviewed By: morehouse

Subscribers: #sanitizers

Tags: #sanitizers

Differential Revision: https://reviews.llvm.org/D78490
This commit is contained in:
Sam Kerner 2020-04-20 17:13:00 -07:00 committed by Matt Morehouse
parent 22219cfc6a
commit e5ce95c660
2 changed files with 48 additions and 5 deletions
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15
compiler-rt/lib/dfsan/dfsan_custom.cpp
View File

@ -157,14 +157,17 @@ SANITIZER_INTERFACE_ATTRIBUTE int
__dfsw_strcasecmp(const char *s1, const char *s2, dfsan_label s1_label, __dfsw_strcasecmp(const char *s1, const char *s2, dfsan_label s1_label,
dfsan_label s2_label, dfsan_label *ret_label) { dfsan_label s2_label, dfsan_label *ret_label) {
for (size_t i = 0;; ++i) { for (size_t i = 0;; ++i) {
if (tolower(s1[i]) != tolower(s2[i]) || s1[i] == 0 || s2[i] == 0) { char s1_lower = tolower(s1[i]);
char s2_lower = tolower(s2[i]);
if (s1_lower != s2_lower || s1[i] == 0 || s2[i] == 0) {
if (flags().strict_data_dependencies) { if (flags().strict_data_dependencies) {
*ret_label = 0; *ret_label = 0;
} else { } else {
*ret_label = dfsan_union(dfsan_read_label(s1, i + 1), *ret_label = dfsan_union(dfsan_read_label(s1, i + 1),
dfsan_read_label(s2, i + 1)); dfsan_read_label(s2, i + 1));
} }
return s1[i] - s2[i]; return s1_lower - s2_lower;
} }
} }
return 0; return 0;
@ -212,15 +215,17 @@ __dfsw_strncasecmp(const char *s1, const char *s2, size_t n,
} }
for (size_t i = 0;; ++i) { for (size_t i = 0;; ++i) {
if (tolower(s1[i]) != tolower(s2[i]) || s1[i] == 0 || s2[i] == 0 || char s1_lower = tolower(s1[i]);
i == n - 1) { char s2_lower = tolower(s2[i]);
if (s1_lower != s2_lower || s1[i] == 0 || s2[i] == 0 || i == n - 1) {
if (flags().strict_data_dependencies) { if (flags().strict_data_dependencies) {
*ret_label = 0; *ret_label = 0;
} else { } else {
*ret_label = dfsan_union(dfsan_read_label(s1, i + 1), *ret_label = dfsan_union(dfsan_read_label(s1, i + 1),
dfsan_read_label(s2, i + 1)); dfsan_read_label(s2, i + 1));
} }
return s1[i] - s2[i]; return s1_lower - s2_lower;
} }
} }
return 0; return 0;

38
compiler-rt/test/dfsan/custom.cpp
View File

@ -207,6 +207,19 @@ void test_strcasecmp() {
#else #else
ASSERT_LABEL(rv, dfsan_union(i_label, j_label)); ASSERT_LABEL(rv, dfsan_union(i_label, j_label));
#endif #endif
char s1[] = "AbZ";
char s2[] = "aBy";
dfsan_set_label(i_label, &s1[2], 1);
dfsan_set_label(j_label, &s2[2], 1);
rv = strcasecmp(s1, s2);
assert(rv > 0); // 'Z' > 'y'
#ifdef STRICT_DATA_DEPENDENCIES
ASSERT_ZERO_LABEL(rv);
#else
ASSERT_LABEL(rv, dfsan_union(i_label, j_label));
#endif
} }
void test_strncasecmp() { void test_strncasecmp() {
@ -225,6 +238,31 @@ void test_strncasecmp() {
rv = strncasecmp(str1, str2, 3); rv = strncasecmp(str1, str2, 3);
assert(rv == 0); assert(rv == 0);
ASSERT_ZERO_LABEL(rv); ASSERT_ZERO_LABEL(rv);
char s1[] = "AbZ";
char s2[] = "aBy";
dfsan_set_label(i_label, &s1[2], 1);
dfsan_set_label(j_label, &s2[2], 1);
rv = strncasecmp(s1, s2, 0);
assert(rv == 0); // Compare zero chars.
ASSERT_ZERO_LABEL(rv);
rv = strncasecmp(s1, s2, 1);
assert(rv == 0); // 'A' == 'a'
ASSERT_ZERO_LABEL(rv);
rv = strncasecmp(s1, s2, 2);
assert(rv == 0); // 'b' == 'B'
ASSERT_ZERO_LABEL(rv);
rv = strncasecmp(s1, s2, 3);
assert(rv > 0); // 'Z' > 'y'
#ifdef STRICT_DATA_DEPENDENCIES
ASSERT_ZERO_LABEL(rv);
#else
ASSERT_LABEL(rv, dfsan_union(i_label, j_label));
#endif
} }
void test_strchr() { void test_strchr() {