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analyzer: fix false leaks when writing through unknown ptrs [PR97072]

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gcc/analyzer/ChangeLog:
	PR analyzer/97072
	* region-model-reachability.cc (reachable_regions::init_cluster):
	Convert symbolic region handling to a switch statement.  Add cases
	to handle SK_UNKNOWN and SK_CONJURED.

gcc/testsuite/ChangeLog:
	PR analyzer/97072
	* gcc.dg/analyzer/pr97072.c: New test.
This commit is contained in:
David Malcolm 2021-01-05 20:54:50 -05:00
parent 23fc2be633
commit ac3966e315
2 changed files with 36 additions and 9 deletions
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36
gcc/analyzer/region-model-reachability.cc
View File

@ -88,20 +88,38 @@ reachable_regions::init_cluster (const region *base_reg)
if (m_store->escaped_p (base_reg))
add (base_reg, true);
/* If BASE_REG is *INIT_VAL(REG) for some other REG, see if REG is
unbound and untouched. If so, then add BASE_REG as a root. */
if (const symbolic_region *sym_reg = base_reg->dyn_cast_symbolic_region ())
{
const svalue *ptr = sym_reg->get_pointer ();
if (const initial_svalue *init_sval = ptr->dyn_cast_initial_svalue ())
switch (ptr->get_kind ())
{
const region *init_sval_reg = init_sval->get_region ();
const region *other_base_reg = init_sval_reg->get_base_region ();
const binding_cluster *other_cluster
= m_store->get_cluster (other_base_reg);
if (other_cluster == NULL
|| !other_cluster->touched_p ())
default:
break;
case SK_INITIAL:
{
/* If BASE_REG is *INIT_VAL(REG) for some other REG, see if REG is
unbound and untouched. If so, then add BASE_REG as a root. */
const initial_svalue *init_sval
= as_a <const initial_svalue *> (ptr);
const region *init_sval_reg = init_sval->get_region ();
const region *other_base_reg = init_sval_reg->get_base_region ();
const binding_cluster *other_cluster
= m_store->get_cluster (other_base_reg);
if (other_cluster == NULL
|| !other_cluster->touched_p ())
add (base_reg, true);
}
break;
case SK_UNKNOWN:
case SK_CONJURED:
{
/* If this cluster is due to dereferencing an unknown/conjured
pointer, any values written through the pointer could still
be live. */
add (base_reg, true);
}
break;
}
}
}

9
gcc/testsuite/gcc.dg/analyzer/pr97072.c Normal file
View File

@ -0,0 +1,9 @@
void unknown_fn_1 (void *);
void test_1 (int co, int y)
{
void *p = __builtin_malloc (1024);
void **q;
unknown_fn_1 (&q);
*q = p;
}