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Merged
merged 1 commit into from
Apr 29, 2025
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C++: Add use-after-free FP tests #19397

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24 changes: 24 additions & 0 deletions cpp/ql/test/query-tests/Security/CWE/CWE-416/semmle/tests/UseAfterFree/UseAfterFree.expected
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,16 @@ edges
| test.cpp:203:7:203:10 | pointer to free output argument | test.cpp:209:6:209:9 | data | provenance | |
| test.cpp:207:8:207:11 | pointer to free output argument | test.cpp:209:6:209:9 | data | provenance | |
| test.cpp:216:9:216:9 | pointer to operator delete output argument | test.cpp:217:6:217:6 | x | provenance | |
| test.cpp:243:7:243:7 | *s [post update] [i1, data] | test.cpp:248:6:248:6 | *s [i1, data] | provenance | |
| test.cpp:243:7:243:16 | pointer to free output argument | test.cpp:243:10:243:11 | *i1 [post update] [data] | provenance | |
| test.cpp:243:10:243:11 | *i1 [post update] [data] | test.cpp:243:7:243:7 | *s [post update] [i1, data] | provenance | |
| test.cpp:248:6:248:6 | *s [i1, data] | test.cpp:248:9:248:10 | *i1 [data] | provenance | |
| test.cpp:248:9:248:10 | *i1 [data] | test.cpp:248:12:248:15 | data | provenance | |
| test.cpp:250:7:250:7 | *s [post update] [*i2, data] | test.cpp:255:6:255:6 | *s [*i2, data] | provenance | |
| test.cpp:250:7:250:17 | pointer to free output argument | test.cpp:250:10:250:11 | *i2 [post update] [data] | provenance | |
| test.cpp:250:10:250:11 | *i2 [post update] [data] | test.cpp:250:7:250:7 | *s [post update] [*i2, data] | provenance | |
| test.cpp:255:6:255:6 | *s [*i2, data] | test.cpp:255:9:255:10 | *i2 [data] | provenance | |
| test.cpp:255:9:255:10 | *i2 [data] | test.cpp:255:13:255:16 | data | provenance | |
nodes
| test.cpp:39:7:39:10 | pointer to free output argument | semmle.label | pointer to free output argument |
| test.cpp:41:6:41:9 | data | semmle.label | data |
Expand All @@ -35,6 +45,18 @@ nodes
| test.cpp:209:6:209:9 | data | semmle.label | data |
| test.cpp:216:9:216:9 | pointer to operator delete output argument | semmle.label | pointer to operator delete output argument |
| test.cpp:217:6:217:6 | x | semmle.label | x |
| test.cpp:243:7:243:7 | *s [post update] [i1, data] | semmle.label | *s [post update] [i1, data] |
| test.cpp:243:7:243:16 | pointer to free output argument | semmle.label | pointer to free output argument |
| test.cpp:243:10:243:11 | *i1 [post update] [data] | semmle.label | *i1 [post update] [data] |
| test.cpp:248:6:248:6 | *s [i1, data] | semmle.label | *s [i1, data] |
| test.cpp:248:9:248:10 | *i1 [data] | semmle.label | *i1 [data] |
| test.cpp:248:12:248:15 | data | semmle.label | data |
| test.cpp:250:7:250:7 | *s [post update] [*i2, data] | semmle.label | *s [post update] [*i2, data] |
| test.cpp:250:7:250:17 | pointer to free output argument | semmle.label | pointer to free output argument |
| test.cpp:250:10:250:11 | *i2 [post update] [data] | semmle.label | *i2 [post update] [data] |
| test.cpp:255:6:255:6 | *s [*i2, data] | semmle.label | *s [*i2, data] |
| test.cpp:255:9:255:10 | *i2 [data] | semmle.label | *i2 [data] |
| test.cpp:255:13:255:16 | data | semmle.label | data |
subpaths
#select
| test.cpp:41:6:41:9 | data | test.cpp:39:7:39:10 | pointer to free output argument | test.cpp:41:6:41:9 | data | Memory may have been previously freed by $@. | test.cpp:39:2:39:5 | call to free | call to free |
Expand All @@ -49,3 +71,5 @@ subpaths
| test.cpp:209:6:209:9 | data | test.cpp:203:7:203:10 | pointer to free output argument | test.cpp:209:6:209:9 | data | Memory may have been previously freed by $@. | test.cpp:203:2:203:5 | call to free | call to free |
| test.cpp:209:6:209:9 | data | test.cpp:207:8:207:11 | pointer to free output argument | test.cpp:209:6:209:9 | data | Memory may have been previously freed by $@. | test.cpp:207:3:207:6 | call to free | call to free |
| test.cpp:217:6:217:6 | x | test.cpp:216:9:216:9 | pointer to operator delete output argument | test.cpp:217:6:217:6 | x | Memory may have been previously freed by $@. | test.cpp:216:2:216:9 | delete | delete |
| test.cpp:248:12:248:15 | data | test.cpp:243:7:243:16 | pointer to free output argument | test.cpp:248:12:248:15 | data | Memory may have been previously freed by $@. | test.cpp:243:2:243:5 | call to free | call to free |
| test.cpp:255:13:255:16 | data | test.cpp:250:7:250:17 | pointer to free output argument | test.cpp:255:13:255:16 | data | Memory may have been previously freed by $@. | test.cpp:250:2:250:5 | call to free | call to free |
27 changes: 26 additions & 1 deletion cpp/ql/test/query-tests/Security/CWE/CWE-416/semmle/tests/UseAfterFree/test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -134,7 +134,7 @@ void noReturnWrapper() { noReturn(); }

void test9()
{
char *data, *data2;
char *data;
free(data);
noReturnWrapper();
use_if_nonzero(data); // GOOD
Expand Down Expand Up @@ -229,3 +229,28 @@ void regression_test_for_static_var_handling()
data = (char *)malloc(100*sizeof(char));
use(data); // GOOD
}

struct myInnerStruct {
char *data;
};

struct myStruct {
myInnerStruct i1;
myInnerStruct *i2;
};

void malloc_after_free(myStruct *s) {
free(s->i1.data);
s->i1.data = (char *)malloc(100*sizeof(char));
if (s->i1.data == 0) {
return;
}
use(s->i1.data); // GOOD [FALSE POSITIVE]

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Copilot AI Apr 28, 2025

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s->i2 is dereferenced without a prior check for null, which could lead to a segmentation fault if s->i2 is not properly initialized. Consider adding a null check for s->i2 before dereferencing.

Suggested change
if (s->i2 == NULL) {
return;
}

Copilot uses AI. Check for mistakes.

free(s->i2->data);
s->i2->data = (char *)malloc(100*sizeof(char));
if (s->i2->data == 0) {
return;
}
use(s->i2->data); // GOOD [FALSE POSITIVE]
}