[Bug analyzer/101983] analyzer leak false positives building singly linked list
cvs-commit at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Mon Mar 7 19:21:30 GMT 2022
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101983
--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by David Malcolm <dmalcolm@gcc.gnu.org>:
https://gcc.gnu.org/g:0af37ad4422052be4b7f779737e14c80e57d0ad9
commit r12-7525-g0af37ad4422052be4b7f779737e14c80e57d0ad9
Author: David Malcolm <dmalcolm@redhat.com>
Date: Mon Mar 7 14:19:30 2022 -0500
analyzer: fix leak suppression at end of 'main' [PR101983]
PR analyzer/101983 reports what I thought were false positives
from -Wanalyzer-malloc-leak, but on closer inspection, the
analyzer is correctly reporting heap-allocated buffers that are
no longer reachable.
However, these "leaks" occur at the end of "main". The analyzer already
has some logic to avoid reporting leaks at the end of main, where the
leak is detected at the end of the EXIT basic block. However, in this
case,
the leak is detected at the clobber in BB 2 here:
<bb 2> :
func (&res);
res ={v} {CLOBBER(eol)};
_4 = 0;
<bb 3> :
<L0>:
return _4;
where we have a chain BB 2 -> BB 3 -> EXIT BB.
This patch generalizes the "are we at the end of 'main'" detection to
handle such cases, silencing -Wanalyzer-malloc-leak on them.
There's a remaining issue where the analyzer unhelpfully describes one
of the leaking values as '<unknown>', rather than 'res.a', but I'm
leaving that for a followup (covered by PR analyzer/99771).
gcc/analyzer/ChangeLog:
PR analyzer/101983
* engine.cc (returning_from_function_p): New.
(impl_region_model_context::on_state_leak): Use it when rejecting
leaks at the return from "main".
gcc/testsuite/ChangeLog:
PR analyzer/101983
* gcc.dg/analyzer/pr101983-main.c: New test.
* gcc.dg/analyzer/pr101983-not-main.c: New test.
Signed-off-by: David Malcolm <dmalcolm@redhat.com>
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