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bbc6d68297
It's an old bug that consists in stale references to symbols remaining in the
GDM if they disappear from other program state sections as a result of any
operation that isn't the actual dead symbol collection. The most common example
here is:
FILE *fp = fopen("myfile.txt", "w");
fp = 0; // leak of file descriptor
In this example the leak were not detected previously because the symbol
disappears from the public part of the program state due to evaluating
the assignment. For that reason the checker never receives a notification
that the symbol is dead, and never reports a leak.
This patch not only causes leak false negatives, but also a number of other
problems, including false positives on some checkers.
What's worse, even though the program state contains a finite number of symbols,
the set of symbols that dies is potentially infinite. This means that is
impossible to compute the set of all dead symbols to pass off to the checkers
for cleaning up their part of the GDM.
No longer compute the dead set at all. Disallow iterating over dead symbols.
Disallow querying if any symbols are dead. Remove the API for marking symbols
as dead, as it is no longer necessary. Update checkers accordingly.
Differential Revision: https://reviews.llvm.org/D18860
llvm-svn: 347953
34 lines
840 B
C++
34 lines
840 B
C++
// RUN: %clang_analyze_cc1 -analyzer-checker=core,osx -analyzer-output=text -verify %s
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// expected-no-diagnostics
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typedef void *CFTypeRef;
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typedef struct _CFURLCacheRef *CFURLCacheRef;
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CFTypeRef CustomCFRetain(CFTypeRef);
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void invalidate(void *);
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struct S1 {
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CFTypeRef s;
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CFTypeRef returnFieldAtPlus0() {
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return s;
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}
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};
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struct S2 {
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S1 *s1;
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};
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void foo(S1 *s1) {
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invalidate(s1);
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S2 s2;
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s2.s1 = s1;
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CustomCFRetain(s1->returnFieldAtPlus0());
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// Definitely no leak end-of-path note here. The retained pointer
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// is still accessible through s1 and s2.
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((void) 0); // no-warning
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// FIXME: Ideally we need to warn after this invalidate(). The per-function
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// retain-release contract is violated: the programmer should release
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// the symbol after it was retained, within the same function.
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invalidate(&s2);
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}
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