{
if (state_machine::state_t state = get_state (sval, ctxt->m_ext_state))
{
- if (!m_sm.can_purge_p (state))
+ if (m_sm.can_purge_p (state))
+ m_map.remove (sval);
+ else
ctxt->on_state_leak (m_sm, sval, state);
- m_map.remove (sval);
}
}
void
sm_state_map::on_liveness_change (const svalue_set &live_svalues,
const region_model *model,
+ const extrinsic_state &ext_state,
impl_region_model_context *ctxt)
{
svalue_set svals_to_unset;
ctxt->on_state_leak (m_sm, sval, e.m_state);
}
+ sm_state_map old_sm_map = *this;
+
for (svalue_set::iterator iter = svals_to_unset.begin ();
iter != svals_to_unset.end (); ++iter)
m_map.remove (*iter);
+
+ /* For state machines like "taint" where states can be
+ alt-inherited from other svalues, ensure that state purging doesn't
+ make us lose sm-state.
+
+ Consider e.g.:
+
+ make_tainted(foo);
+ if (foo.field > 128)
+ return;
+ arr[foo.field].f1 = v1;
+
+ where the last line is:
+
+ (A): _t1 = foo.field;
+ (B): _t2 = _t1 * sizeof(arr[0]);
+ (C): [arr + _t2].f1 = val;
+
+ At (A), foo is 'tainted' and foo.field is 'has_ub'.
+ After (B), foo.field's value (in _t1) is no longer directly
+ within LIVE_SVALUES, so with state purging enabled, we would
+ erroneously purge the "has_ub" state from the svalue.
+
+ Given that _t2's value's state comes from _t1's value's state,
+ we need to preserve that information.
+
+ Hence for all svalues that have had their explicit sm-state unset,
+ having their sm-state being unset, determine if doing so has changed
+ their effective state, and if so, explicitly set their state.
+
+ For example, in the above, unsetting the "has_ub" for _t1's value means
+ that _t2's effective value changes from "has_ub" (from alt-inherited
+ from _t1's value) to "tainted" (inherited from "foo"'s value).
+
+ For such cases, preserve the effective state by explicitly setting the
+ new state. In the above example, this means explicitly setting _t2's
+ value to the value ("has_ub") it was previously alt-inheriting from _t1's
+ value. */
+ if (m_sm.has_alt_get_inherited_state_p ())
+ {
+ auto_vec<const svalue *> svalues_needing_state;
+ for (auto unset_sval : svals_to_unset)
+ {
+ const state_machine::state_t old_state
+ = old_sm_map.get_state (unset_sval, ext_state);
+ const state_machine::state_t new_state
+ = get_state (unset_sval, ext_state);
+ if (new_state != old_state)
+ svalues_needing_state.safe_push (unset_sval);
+ }
+ for (auto sval : svalues_needing_state)
+ {
+ const state_machine::state_t old_state
+ = old_sm_map.get_state (sval, ext_state);
+ impl_set_state (sval, old_state, nullptr, ext_state);
+ }
+ }
}
/* Purge state from SVAL (in response to a call to an unknown function). */
--- /dev/null
+/* Reduced from false positive in Linux kernel in
+ drivers/scsi/aacraid/aachba.c. */
+
+/* { dg-do compile } */
+/* { dg-options "-fanalyzer" } */
+/* { dg-require-effective-target analyzer } */
+
+typedef unsigned char u8;
+typedef unsigned int u32;
+
+extern unsigned long
+copy_from_user(void* to, const void* from, unsigned long n);
+
+struct fsa_dev_info
+{
+ u8 valid;
+ u8 deleted;
+};
+struct aac_dev
+{
+ int maximum_num_containers;
+ struct fsa_dev_info* fsa_dev;
+};
+struct aac_delete_disk
+{
+ u32 disknum;
+ u32 cnum;
+};
+int
+force_delete_disk(struct aac_dev* dev, void* arg)
+{
+ struct aac_delete_disk dd;
+ struct fsa_dev_info* fsa_dev_ptr;
+ fsa_dev_ptr = dev->fsa_dev;
+ if (!fsa_dev_ptr)
+ return -16;
+ if (copy_from_user(&dd, arg, sizeof(struct aac_delete_disk)))
+ return -14;
+ if (dd.cnum >= dev->maximum_num_containers)
+ return -22;
+ fsa_dev_ptr[dd.cnum].deleted = 1;
+ fsa_dev_ptr[dd.cnum].valid = 0; /* { dg-bogus "use of attacker-controlled value as offset without upper-bounds checking" } */
+ return 0;
+}