https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106147
Bug ID: 106147
Summary: RFE: -fanalyzer could complain about some cases of
infinite loops and infinite recursion
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: analyzer
Assignee: dmalcolm at gcc dot gnu.org
Reporter: dmalcolm at gcc dot gnu.org
Target Milestone: ---
We can't solve the halting problem, but maybe we can detect some cases where
the code *definitely* loops forever or has infinite recursion, where there are
no state changes or possible interactions with the outside world.
See:
https://cwe.mitre.org/data/definitions/674.html
and:
https://cwe.mitre.org/data/definitions/835.html
Juliet 1.3 has testcases for:
(a) CWE674_Uncontrolled_Recursion/
(b) CWE835_Infinite_Loop/
where (a) makes a distinction between actually unbounded vs a buggy loop that
counts down from UINT_MAX (pushing UINT_MAX stack frames is probably going to
crash).
All of the test cases in (b) perform output in an infinite loop, which I'd
argue is not a bug, as the program is generating output that's visible to the
outside world.
Compare CWE 835 examples 1 and 2. Example 1 repeatedly calls "connect" in a
loop, which I don't think -fanalyzer is going to be able to reason about,
whereas 2 has logic:
while (inventoryCount > minimumCount) {
inventoryCount = inventoryCount - rateSold;
days++;
}
where if rateSold is 0, this effectively becomes:
while (inventoryCount > minimumCount) {
days++;
}
and thus an infinite loop with no observable effects; possible interaction with
taint (e.g. if rateSold is under attacker control)
