@@ -1244,6 +1244,31 @@ exploded_node::on_stmt (exploded_graph &eg,
sm_state_map *new_smap = state->m_checker_states[sm_idx];
impl_sm_context sm_ctxt (eg, sm_idx, sm, this, &old_state, state,
old_smap, new_smap);
+
+ /* If we're at the def-stmt of an SSA name, then potentially purge
+ any sm-state for svalues that involve that SSA name. This avoids
+ false positives in loops, since a symbolic value referring to the
+ SSA name will be referring to the previous value of that SSA name.
+ For example, in:
+ while ((e = hashmap_iter_next(&iter))) {
+ struct oid2strbuf *e_strbuf = (struct oid2strbuf *)e;
+ free (e_strbuf->value);
+ }
+ at the def-stmt of e_8:
+ e_8 = hashmap_iter_next (&iter);
+ we should purge the "freed" state of:
+ INIT_VAL(CAST_REG(‘struct oid2strbuf’, (*INIT_VAL(e_8))).value)
+ which is the "e_strbuf->value" value from the previous iteration,
+ or we will erroneously report a double-free - the "e_8" within it
+ refers to the previous value. */
+ if (tree lhs = gimple_get_lhs (stmt))
+ if (TREE_CODE (lhs) == SSA_NAME)
+ {
+ const svalue *sval
+ = old_state.m_region_model->get_rvalue (lhs, &ctxt);
+ new_smap->purge_state_involving (sval, eg.get_ext_state ());
+ }
+
/* Allow the state_machine to handle the stmt. */
if (sm.on_stmt (&sm_ctxt, snode, stmt))
unknown_side_effects = false;
@@ -586,6 +586,36 @@ sm_state_map::on_unknown_change (const svalue *sval,
impl_set_state (*iter, (state_machine::state_t)0, NULL, ext_state);
}
+/* Purge state for things involving SVAL.
+ For use when SVAL changes meaning, at the def_stmt on an SSA_NAME. */
+
+void
+sm_state_map::purge_state_involving (const svalue *sval,
+ const extrinsic_state &ext_state)
+{
+ /* Currently svalue::involves_p requires this. */
+ if (sval->get_kind () != SK_INITIAL)
+ return;
+
+ svalue_set svals_to_unset;
+
+ for (map_t::iterator iter = m_map.begin ();
+ iter != m_map.end ();
+ ++iter)
+ {
+ const svalue *key = (*iter).first;
+ entry_t e = (*iter).second;
+ if (!m_sm.can_purge_p (e.m_state))
+ continue;
+ if (key->involves_p (sval))
+ svals_to_unset.add (key);
+ }
+
+ for (svalue_set::iterator iter = svals_to_unset.begin ();
+ iter != svals_to_unset.end (); ++iter)
+ impl_set_state (*iter, (state_machine::state_t)0, NULL, ext_state);
+}
+
/* Comparator for imposing an order on sm_state_map instances. */
int
@@ -157,6 +157,9 @@ public:
bool is_mutable,
const extrinsic_state &ext_state);
+ void purge_state_involving (const svalue *sval,
+ const extrinsic_state &ext_state);
+
iterator_t begin () const { return m_map.begin (); }
iterator_t end () const { return m_map.end (); }
size_t elements () const { return m_map.elements (); }
@@ -5114,6 +5114,37 @@ test_alloca ()
ASSERT_EQ (model.get_rvalue (p, &ctxt)->get_kind (), SK_POISONED);
}
+/* Verify that svalue::involves_p works. */
+
+static void
+test_involves_p ()
+{
+ region_model_manager mgr;
+ tree int_star = build_pointer_type (integer_type_node);
+ tree p = build_global_decl ("p", int_star);
+ tree q = build_global_decl ("q", int_star);
+
+ test_region_model_context ctxt;
+ region_model model (&mgr);
+ const svalue *p_init = model.get_rvalue (p, &ctxt);
+ const svalue *q_init = model.get_rvalue (q, &ctxt);
+
+ ASSERT_TRUE (p_init->involves_p (p_init));
+ ASSERT_FALSE (p_init->involves_p (q_init));
+
+ const region *star_p_reg = mgr.get_symbolic_region (p_init);
+ const region *star_q_reg = mgr.get_symbolic_region (q_init);
+
+ const svalue *init_star_p = mgr.get_or_create_initial_value (star_p_reg);
+ const svalue *init_star_q = mgr.get_or_create_initial_value (star_q_reg);
+
+ ASSERT_TRUE (init_star_p->involves_p (p_init));
+ ASSERT_FALSE (p_init->involves_p (init_star_p));
+ ASSERT_FALSE (init_star_p->involves_p (q_init));
+ ASSERT_TRUE (init_star_q->involves_p (q_init));
+ ASSERT_FALSE (init_star_q->involves_p (p_init));
+}
+
/* Run all of the selftests within this file. */
void
@@ -5150,6 +5181,7 @@ analyzer_region_model_cc_tests ()
test_POINTER_PLUS_EXPR_then_MEM_REF ();
test_malloc ();
test_alloca ();
+ test_involves_p ();
}
} // namespace selftest
@@ -481,6 +481,40 @@ svalue::cmp_ptr_ptr (const void *p1, const void *p2)
return cmp_ptr (sval1, sval2);
}
+/* Subclass of visitor for use in implementing svalue::involves_p. */
+
+class involvement_visitor : public visitor
+{
+public:
+ involvement_visitor (const svalue *needle)
+ : m_needle (needle), m_found (false) {}
+
+ void visit_initial_svalue (const initial_svalue *candidate)
+ {
+ if (candidate == m_needle)
+ m_found = true;
+ }
+
+ bool found_p () const { return m_found; }
+
+private:
+ const svalue *m_needle;
+ bool m_found;
+};
+
+/* Return true iff this svalue is defined in terms of OTHER. */
+
+bool
+svalue::involves_p (const svalue *other) const
+{
+ /* Currently only implemented for initial_svalue. */
+ gcc_assert (other->get_kind () == SK_INITIAL);
+
+ involvement_visitor v (other);
+ accept (&v);
+ return v.found_p ();
+}
+
/* class region_svalue : public svalue. */
/* Implementation of svalue::dump_to_pp vfunc for region_svalue. */
@@ -136,6 +136,8 @@ public:
static int cmp_ptr (const svalue *, const svalue *);
static int cmp_ptr_ptr (const void *, const void *);
+ bool involves_p (const svalue *other) const;
+
protected:
svalue (complexity c, tree type)
: m_complexity (c), m_type (type)
@@ -192,9 +192,7 @@ static int ath10k_usb_hif_tx_sg(struct ath10k *ar, u8 pipe_id,
goto err_free_urb_to_pipe;
}
- /* TODO: the loop confuses the double-free checker (another
- instance of PR analyzer/93695). */
- usb_free_urb(urb); /* { dg-bogus "double-'usb_free_urb' of 'urb'" "" { xfail *-*-* } } */
+ usb_free_urb(urb); /* { dg-bogus "double-'usb_free_urb' of 'urb'" } */
}
return 0;
new file mode 100644
@@ -0,0 +1,53 @@
+/* { dg-additional-options "-Wno-analyzer-too-complex" } */
+/* TODO: remove the need for this option (PR analyzer/93695). */
+
+#define NELEMS 10
+#define ARRAY_SIZE(a) (sizeof (a) / sizeof (a[0]))
+
+void
+test_1 (void)
+{
+ int *p[NELEMS];
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE (p); ++i)
+ p[i] = __builtin_malloc (sizeof (i));
+
+ for (i = 0; i < ARRAY_SIZE (p); ++i)
+ __builtin_free (p [i]);
+}
+
+void
+test_2 (int n)
+{
+ int **p;
+ int i;
+
+ p = (int **)__builtin_malloc (sizeof (int *) * n);
+ if (!p)
+ return;
+
+ for (i = 0; i < n; ++i)
+ p[i] = __builtin_malloc (sizeof (i));
+
+ for (i = 0; i < n; ++i)
+ __builtin_free (p [i]);
+
+ __builtin_free (p);
+}
+
+void
+test_3 (int **p, int n)
+{
+ int i;
+ for (i = 0; i < n; ++i)
+ p[i] = __builtin_malloc (sizeof (i));
+}
+
+void
+test_4 (void **p, int n)
+{
+ int i;
+ for (i = 0; i < n; ++i)
+ __builtin_free (p[i]);
+}
new file mode 100644
@@ -0,0 +1,60 @@
+#include <stdlib.h>
+
+struct hashmap_entry {
+ struct hashmap_entry *next;
+ unsigned int hash;
+};
+
+struct strbuf {
+ size_t alloc;
+ size_t len;
+ char *buf;
+};
+
+struct oid2strbuf {
+ struct hashmap_entry ent; /* must be the first member! */
+ unsigned char key[21];
+ struct strbuf *value;
+};
+
+
+struct hashmap_iter {
+ struct hashmap *map;
+ struct hashmap_entry *next;
+ unsigned int tablepos;
+};
+
+struct hashmap {
+ struct hashmap_entry **table;
+ // hashmap_cmp_fn cmpfn;
+ unsigned int size, tablesize, grow_at, shrink_at;
+ unsigned disallow_rehash : 1;
+};
+void strbuf_init(struct strbuf *, size_t);
+void *hashmap_iter_next(struct hashmap_iter *iter);
+void hashmap_free(struct hashmap *map, int free_entries);
+void hashmap_iter_init(struct hashmap *map, struct hashmap_iter *iter);
+
+void strbuf_release(struct strbuf *sb)
+{
+ if (sb->alloc) { /* { dg-bogus "use after 'free'" } */
+ free(sb->buf);
+ strbuf_init(sb, 0);
+ }
+}
+
+void oid2strbuf_free(struct hashmap *map) {
+ struct hashmap_iter iter;
+ struct hashmap_entry *e;
+
+ hashmap_iter_init(map, &iter);
+ while ((e = hashmap_iter_next(&iter))) {
+ struct oid2strbuf *e_strbuf = (struct oid2strbuf *)e;
+ strbuf_release(e_strbuf->value); /* { dg-bogus "use after 'free'" } */
+ free(e_strbuf->value);
+ free(e);
+ }
+
+ hashmap_free(map, 0);
+}
+
new file mode 100644
@@ -0,0 +1,42 @@
+struct node
+{
+ struct node *next;
+};
+
+void test_1 (struct node *n)
+{
+ while (n)
+ {
+ struct node *next = n->next;
+ __builtin_free (n);
+ n = next;
+ }
+}
+
+extern void *get_ptr (void);
+
+void test_2 (void)
+{
+ void *p;
+ while (p = get_ptr ())
+ __builtin_free (p); /* { dg-bogus "double-'free' of 'p'" } */
+}
+
+extern void **get_ptr_ptr (void);
+
+void test_3 (void)
+{
+ void **p;
+ while (p = get_ptr_ptr ())
+ __builtin_free (*p); /* { dg-bogus "double-'free'" } */
+}
+
+void test_4 (void)
+{
+ void *p = (void *)0;
+ while (1)
+ {
+ __builtin_free (p); /* { dg-bogus "double-'free' of 'p'" } */
+ p = get_ptr ();
+ }
+}
new file mode 100644
@@ -0,0 +1,40 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+void
+test_1 (void)
+{
+ int i;
+
+ for (i = 0; i < 2; ++i) {
+ FILE *fp = fopen ("/tmp/test", "w");
+ fprintf (fp, "hello:%s ", "world");
+ fclose (fp); /* { dg-bogus "double 'fclose'" } */
+ }
+}
+
+void
+test_2 (void)
+{
+ int i;
+
+ for (i = 0; i < 2; ++i) {
+ FILE *fp = fopen ("/tmp/test", "w");
+ fprintf (fp, "hello");
+ }
+} /* { dg-warning "leak of FILE 'fp'" } */
+
+FILE *fp3;
+
+void
+test_3 (FILE **fpp)
+{
+ int i;
+
+ for (i = 0; i < 2; ++i) {
+ *fpp = fopen ("/tmp/test", "w");
+ fprintf (*fpp, "hello");
+ fclose (*fpp); /* { dg-bogus "double 'fclose'" } */
+ *fpp = NULL;
+ }
+}
new file mode 100644
@@ -0,0 +1,34 @@
+/* Reduced from
+ https://github.com/libguestfs/libguestfs/blob/e0a11061035d47b118c95706240bcc17fd576edc/tests/mount-local/test-parallel-mount-local.c#L299-L335
+ which is GPLv2 or later. */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+extern int foo (void);
+
+void
+test_mountpoint (const char *mp)
+{
+ const int nr_passes = 5 + (random () & 31);
+ int pass;
+ int ret = 1;
+ FILE *fp;
+
+ for (pass = 0; pass < nr_passes; ++pass) {
+ if (foo ()) {
+ goto error;
+ }
+ fp = fopen ("file", "w");
+ if (fp == NULL) {
+ goto error;
+ }
+ fprintf (fp, "hello world\n");
+ fclose (fp); /* { dg-bogus "double 'fclose'" } */
+ }
+
+ ret = 0;
+
+ error:
+ exit (ret);
+}
new file mode 100644
@@ -0,0 +1,16 @@
+#include <stdlib.h>
+
+extern void foo (void *);
+
+void
+test_1 (int nr_passes)
+{
+ int pass;
+ void *p;
+
+ for (pass = 0; pass < nr_passes; ++pass) {
+ p = malloc (1024);
+ foo (p);
+ free (p);
+ }
+}
Various false positives from -fanalyzer involve SSA names in loops, where sm-state associated with an SSA name from one iteration is erroneously reused in a subsequent iteration. For example, PR analyzer/99716 describes a false "double 'fclose' of FILE 'fp'" on: for (i = 0; i < 2; ++i) { FILE *fp = fopen ("/tmp/test", "w"); fprintf (fp, "hello"); fclose (fp); } where the gimple of the loop body is: fp_7 = fopen ("/tmp/test", "w"); __builtin_fwrite ("hello", 1, 5, fp_7); fclose (fp_7); i_10 = i_1 + 1; where fp_7 transitions to "closed" at the fclose, but is not reset at the subsequent fopen, leading to the false positive when the fclose is re-reached. The fix is to reset sm-state for svalues that involve an SSA name at the SSA name's def-stmt, since the def-stmt effectively changes the meaning of those related svalues. Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu. Pushed to trunk as r11-7820-g71fc4655ab86ab66b40165b2cb49c1395ca82a9a. gcc/analyzer/ChangeLog: PR analyzer/93695 PR analyzer/99044 PR analyzer/99716 * engine.cc (exploded_node::on_stmt): Clear sm-state involving an SSA name at the def-stmt of that SSA name. * program-state.cc (sm_state_map::purge_state_involving): New. * program-state.h (sm_state_map::purge_state_involving): New decl. * region-model.cc (selftest::test_involves_p): New. (selftest::analyzer_region_model_cc_tests): Call it. * svalue.cc (class involvement_visitor): New class (svalue::involves_p): New. * svalue.h (svalue::involves_p): New decl. gcc/testsuite/ChangeLog: PR analyzer/93695 PR analyzer/99044 PR analyzer/99716 * gcc.dg/analyzer/attr-malloc-CVE-2019-19078-usb-leak.c: Remove xfail. * gcc.dg/analyzer/pr93695-1.c: New test. * gcc.dg/analyzer/pr99044-1.c: New test. * gcc.dg/analyzer/pr99044-2.c: New test. * gcc.dg/analyzer/pr99716-1.c: New test. * gcc.dg/analyzer/pr99716-2.c: New test. * gcc.dg/analyzer/pr99716-3.c: New test. --- gcc/analyzer/engine.cc | 25 ++++++++ gcc/analyzer/program-state.cc | 30 ++++++++++ gcc/analyzer/program-state.h | 3 + gcc/analyzer/region-model.cc | 32 ++++++++++ gcc/analyzer/svalue.cc | 34 +++++++++++ gcc/analyzer/svalue.h | 2 + .../attr-malloc-CVE-2019-19078-usb-leak.c | 4 +- gcc/testsuite/gcc.dg/analyzer/pr93695-1.c | 53 ++++++++++++++++ gcc/testsuite/gcc.dg/analyzer/pr99044-1.c | 60 +++++++++++++++++++ gcc/testsuite/gcc.dg/analyzer/pr99044-2.c | 42 +++++++++++++ gcc/testsuite/gcc.dg/analyzer/pr99716-1.c | 40 +++++++++++++ gcc/testsuite/gcc.dg/analyzer/pr99716-2.c | 34 +++++++++++ gcc/testsuite/gcc.dg/analyzer/pr99716-3.c | 16 +++++ 13 files changed, 372 insertions(+), 3 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/analyzer/pr93695-1.c create mode 100644 gcc/testsuite/gcc.dg/analyzer/pr99044-1.c create mode 100644 gcc/testsuite/gcc.dg/analyzer/pr99044-2.c create mode 100644 gcc/testsuite/gcc.dg/analyzer/pr99716-1.c create mode 100644 gcc/testsuite/gcc.dg/analyzer/pr99716-2.c create mode 100644 gcc/testsuite/gcc.dg/analyzer/pr99716-3.c