3 Commits

Author	SHA1	Message	Date
Frantisek Sumsal	c8fec8bf9b	lgtm: detect more possible problematic scenarios ... 1) don't ignore stack-allocated variables, since they may hide heap-allocated stuff (compound types) 2) check if there's a return between the variable declaration and its initialization; if so, treat the variable as uninitialized 3) introduction of 2) increased the query runtime exponentially, so introduce some optimizations to bring it back to some reasonable values	2021-12-05 22:47:14 +01:00
Frantisek Sumsal	af18682136	lgtm: ignore certain cleanup functions ... as they don't do any illegal stuff even when used with an uninitialized variable.	2021-12-05 15:53:22 +01:00
Frantisek Sumsal	863bff7548	lgtm: detect uninitialized variables using the __cleanup__ attribute ... This is a slightly modified version of the original `cpp/uninitialized-local` CodeQL query which focuses only on variables using the cleanup macros. Since this has proven to cause issues in the past, let's panic on every uninitialized variable using any of the cleanup macros (as long as they're written using the __cleanup__ attribute). Some test results from a test I used when writing the query: ``` #define _cleanup_foo_ __attribute__((__cleanup__(foo))) #define _cleanup_(x) __attribute__((__cleanup__(x))) static inline void freep(void *p) { *(void**)p = mfree(*(void**) p); } #define _cleanup_free_ _cleanup_(freep) static inline void foo(char **p) { if (*p) *p = free(*p); } int main(void) { __attribute__((__cleanup__(foo))) char *a; char *b; _cleanup_foo_ char *c; char **d; _cleanup_free_ char *e; int r; r = fun(&e); if (r < 0) return 1; puts(a); puts(b); puts(c); puts(*d); puts(e); return 0; } ``` ``` +| test.c:23:14:23:14 | e | The variable $@ may not be initialized here, but has a cleanup handler. | test.c:20:26:20:26 | e | e | +| test.c:27:10:27:10 | a | The variable $@ may not be initialized here, but has a cleanup handler. | test.c:16:45:16:45 | a | a | +| test.c:29:10:29:10 | c | The variable $@ may not be initialized here, but has a cleanup handler. | test.c:18:25:18:25 | c | c | ```	2021-12-02 16:56:54 +01:00