As per David's suggestion.
- Improved leading comment of "is_placement_new_p"
- "kf_operator_new::matches_call_types_p" now checks that arg 0 is of
integral type and that arg 1, if any, is of pointer type.
- Changed ambiguous "int" to "int8_t" and "int64_t" in placement-new-size.C
to trigger a target independent out-of-bounds warning.
Other OOB tests were not based on the size of types, but on the number
elements, so them using "int" didn't lead to any ambiguity.
contrib/check_GNU_style.sh still complains about a space before square
brackets in string "operator new []", but as before, this one space is
mandatory for a correct recognition of the function.
Changes succesfully regstrapped on x86_64-linux-gnu against trunk
3c776fdf1a8.
Is it OK for trunk ?
Thanks again,
Benjamin.
---
Fixed spurious possibly-NULL warning always tagging along throwing
operator new despite it never returning NULL.
Now, operator new is correctly recognized as possibly returning
NULL if and only if it is non-throwing or exceptions have been disabled.
Different standard signatures of operator new are now properly recognized.
Added support of placement new, so that is now properly recognized,
and a 'heap_allocated' region is no longer created for it.
Placement new size is also checked and a 'Wanalyzer-allocation-size'
is emitted when relevant, as well as always a 'Wanalyzer-out-of-bounds'.
gcc/analyzer/ChangeLog:
PR analyzer/105948
* analyzer.h (is_placement_new_p): New declaration.
* call-details.cc
(call_details::maybe_get_arg_region): New function.
Returns the region of the argument at given index if possible.
* call-details.h: Declaration of above function.
* kf-lang-cp.cc (is_placement_new_p): Returns true if the
gcall is recognized as a placement new.
* region-model.cc (region_model::eval_condition):
Now recursively call itself if one the operand is wrapped in a cast.
* sm-malloc.cc (malloc_state_machine::on_stmt): Added
recognition of placement new.
gcc/testsuite/ChangeLog:
PR analyzer/105948
* g++.dg/analyzer/out-of-bounds-placement-new.C: Added a directive.
* g++.dg/analyzer/placement-new.C: Added tests.
* g++.dg/analyzer/new-2.C: New test.
* g++.dg/analyzer/noexcept-new.C: New test.
* g++.dg/analyzer/placement-new-size.C: New test.
Signed-off-by: benjamin priour <priour...@gmail.com>
---
gcc/analyzer/analyzer.h | 1 +
gcc/analyzer/call-details.cc | 11 ++
gcc/analyzer/call-details.h | 1 +
gcc/analyzer/kf-lang-cp.cc | 105 +++++++++++++++++-
gcc/analyzer/region-model.cc | 21 ++++
gcc/analyzer/sm-malloc.cc | 17 ++-
gcc/testsuite/g++.dg/analyzer/new-2.C | 50 +++++++++
gcc/testsuite/g++.dg/analyzer/noexcept-new.C | 48 ++++++++
.../analyzer/out-of-bounds-placement-new.C | 2 +-
.../g++.dg/analyzer/placement-new-size.C | 27 +++++
gcc/testsuite/g++.dg/analyzer/placement-new.C | 63 ++++++++++-
11 files changed, 332 insertions(+), 14 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/analyzer/new-2.C
create mode 100644 gcc/testsuite/g++.dg/analyzer/noexcept-new.C
create mode 100644 gcc/testsuite/g++.dg/analyzer/placement-new-size.C
diff --git a/gcc/analyzer/analyzer.h b/gcc/analyzer/analyzer.h
index 579517c23e6..b86e5cac74d 100644
--- a/gcc/analyzer/analyzer.h
+++ b/gcc/analyzer/analyzer.h
@@ -391,6 +391,7 @@ extern bool is_std_named_call_p (const_tree fndecl, const
char *funcname,
const gcall *call, unsigned int num_args);
extern bool is_setjmp_call_p (const gcall *call);
extern bool is_longjmp_call_p (const gcall *call);
+extern bool is_placement_new_p (const gcall *call);
extern const char *get_user_facing_name (const gcall *call);
diff --git a/gcc/analyzer/call-details.cc b/gcc/analyzer/call-details.cc
index 17edaf26276..01f061d774e 100644
--- a/gcc/analyzer/call-details.cc
+++ b/gcc/analyzer/call-details.cc
@@ -152,6 +152,17 @@ call_details::get_arg_svalue (unsigned idx) const
return m_model->get_rvalue (arg, m_ctxt);
}
+/* If argument IDX's svalue at the callsite is a region_svalue,
+ return the region it points to.
+ Otherwise return NULL. */
+
+const region *
+call_details::maybe_get_arg_region (unsigned idx) const
+{
+ const svalue *sval = get_arg_svalue (idx);
+ return sval->maybe_get_region ();
+}
+
/* Attempt to get the string literal for argument IDX, or return NULL
otherwise.
For use when implementing "__analyzer_*" functions that take
diff --git a/gcc/analyzer/call-details.h b/gcc/analyzer/call-details.h
index 14a206ff5d6..aac2b7d33d8 100644
--- a/gcc/analyzer/call-details.h
+++ b/gcc/analyzer/call-details.h
@@ -55,6 +55,7 @@ public:
tree get_arg_tree (unsigned idx) const;
tree get_arg_type (unsigned idx) const;
const svalue *get_arg_svalue (unsigned idx) const;
+ const region *maybe_get_arg_region (unsigned idx) const;
const char *get_arg_string_literal (unsigned idx) const;
tree get_fndecl_for_call () const;
diff --git a/gcc/analyzer/kf-lang-cp.cc b/gcc/analyzer/kf-lang-cp.cc
index 393b4f25e79..ef057da863f 100644
--- a/gcc/analyzer/kf-lang-cp.cc
+++ b/gcc/analyzer/kf-lang-cp.cc
@@ -35,6 +35,49 @@ along with GCC; see the file COPYING3. If not see
#if ENABLE_ANALYZER
+/* Return true if CALL is a non-allocating operator new or operator new []
+ that contains no user-defined args, i.e. having any signature of:
+
+ - void* operator new (std::size_t count, void* ptr);
+ - void* operator new[] (std::size_t count, void* ptr);
+
+ See https://en.cppreference.com/w/cpp/memory/new/operator_new. */
+
+bool is_placement_new_p (const gcall *call)
+{
+ gcc_assert (call);
+
+ tree fndecl = gimple_call_fndecl (call);
+ if (!fndecl)
+ return false;
+
+ if (!is_named_call_p (fndecl, "operator new", call, 2)
+ && !is_named_call_p (fndecl, "operator new []", call, 2))
+ return false;
+ tree arg1 = gimple_call_arg (call, 1);
+
+ if (!POINTER_TYPE_P (TREE_TYPE (arg1)))
+ return false;
+
+ /* We must distinguish between an allocating non-throwing new
+ and a non-allocating new.
+
+ The former might have one of the following signatures :
+ void* operator new (std::size_t count, const std::nothrow_t& tag);
+ void* operator new[] (std::size_t count, const std::nothrow_t& tag);
+
+ However, debugging has shown that TAG is actually a POINTER_TYPE,
+ not a REFERENCE_TYPE.
+
+ Thus, we cannot easily differentiate the types, but we instead have to
+ check if the second argument's type identifies as nothrow_t. */
+ tree identifier = TYPE_IDENTIFIER (TREE_TYPE (TREE_TYPE (arg1)));
+ if (!identifier)
+ return true;
+ const char *name = IDENTIFIER_POINTER (identifier);
+ return 0 != strcmp (name, "nothrow_t");
+}
+
namespace ana {
/* Implementations of specific functions. */
@@ -46,7 +89,11 @@ class kf_operator_new : public known_function
public:
bool matches_call_types_p (const call_details &cd) const final override
{
- return cd.num_args () == 1;
+ return (cd.num_args () == 1
+ && cd.arg_is_size_p (0))
+ || (cd.num_args () == 2
+ && cd.arg_is_size_p (0)
+ && POINTER_TYPE_P (cd.get_arg_type (1)));
}
void impl_call_pre (const call_details &cd) const final override
@@ -54,13 +101,61 @@ public:
region_model *model = cd.get_model ();
region_model_manager *mgr = cd.get_manager ();
const svalue *size_sval = cd.get_arg_svalue (0);
- const region *new_reg
- = model->get_or_create_region_for_heap_alloc (size_sval, cd.get_ctxt ());
- if (cd.get_lhs_type ())
+ region_model_context *ctxt = cd.get_ctxt ();
+ const gcall *call = cd.get_call_stmt ();
+
+ /* If the call was actually a placement new, check that accessing
+ the buffer lhs is placed into does not result in out-of-bounds. */
+ if (is_placement_new_p (call))
{
+ const region *ptr_reg = cd.maybe_get_arg_region (1);
+ if (ptr_reg && cd.get_lhs_type ())
+ {
+ const region *base_reg = ptr_reg->get_base_region ();
+ const svalue *num_bytes_sval = cd.get_arg_svalue (0);
+ const region *sized_new_reg = mgr->get_sized_region (base_reg,
+ cd.get_lhs_type (),
+ num_bytes_sval);
+ model->check_region_for_write (sized_new_reg,
+ nullptr,
+ ctxt);
const svalue *ptr_sval
- = mgr->get_ptr_svalue (cd.get_lhs_type (), new_reg);
+ = mgr->get_ptr_svalue (cd.get_lhs_type (), sized_new_reg);
cd.maybe_set_lhs (ptr_sval);
+ }
+ }
+ /* If the call is an allocating new, then create a heap allocated
+ region. */
+ else
+ {
+ const region *new_reg
+ = model->get_or_create_region_for_heap_alloc (size_sval, ctxt);
+ if (cd.get_lhs_type ())
+ {
+ const svalue *ptr_sval
+ = mgr->get_ptr_svalue (cd.get_lhs_type (), new_reg);
+ cd.maybe_set_lhs (ptr_sval);
+ }
+ }
+
+ }
+
+ void impl_call_post (const call_details &cd) const final override
+ {
+ region_model *model = cd.get_model ();
+ region_model_manager *mgr = cd.get_manager ();
+ tree callee_fndecl = cd.get_fndecl_for_call ();
+ region_model_context *ctxt = cd.get_ctxt ();
+
+ /* If the call is guaranteed to return nonnull
+ then add a nonnull constraint to the allocated region. */
+ if (!TREE_NOTHROW (TREE_TYPE (callee_fndecl)) && flag_exceptions)
+ {
+ const svalue *nonnull
+ = mgr->get_or_create_null_ptr (cd.get_lhs_type ());
+ const svalue *result
+ = model->get_store_value (cd.get_lhs_region (), ctxt);
+ model->add_constraint (result, NE_EXPR, nonnull, ctxt);
}
}
};
diff --git a/gcc/analyzer/region-model.cc b/gcc/analyzer/region-model.cc
index 187013a37cc..599178e3d86 100644
--- a/gcc/analyzer/region-model.cc
+++ b/gcc/analyzer/region-model.cc
@@ -3479,6 +3479,27 @@ region_model::eval_condition (const svalue *lhs,
}
}
+ /* Attempt to unwrap cast if there is one, and the types match. */
+ tree lhs_type = lhs->get_type ();
+ tree rhs_type = rhs->get_type ();
+ if (lhs_type && rhs_type)
+ {
+ const unaryop_svalue *lhs_un_op = dyn_cast <const unaryop_svalue *> (lhs);
+ const unaryop_svalue *rhs_un_op = dyn_cast <const unaryop_svalue *> (rhs);
+ if (lhs_un_op && CONVERT_EXPR_CODE_P (lhs_un_op->get_op ())
+ && rhs_un_op && CONVERT_EXPR_CODE_P (rhs_un_op->get_op ())
+ && lhs_type == rhs_type)
+ return eval_condition (lhs_un_op->get_arg (), op, rhs_un_op->get_arg ());
+
+ else if (lhs_un_op && CONVERT_EXPR_CODE_P (lhs_un_op->get_op ())
+ && lhs_type == rhs_type)
+ return eval_condition (lhs_un_op->get_arg (), op, rhs);
+
+ else if (rhs_un_op && CONVERT_EXPR_CODE_P (rhs_un_op->get_op ())
+ && lhs_type == rhs_type)
+ return eval_condition (lhs, op, rhs_un_op->get_arg ());
+ }
+
/* Otherwise, try constraints.
Cast to const to ensure we don't change the constraint_manager as we
do this (e.g. by creating equivalence classes). */
diff --git a/gcc/analyzer/sm-malloc.cc b/gcc/analyzer/sm-malloc.cc
index a8c63eb1ce8..41c313c07dd 100644
--- a/gcc/analyzer/sm-malloc.cc
+++ b/gcc/analyzer/sm-malloc.cc
@@ -754,7 +754,7 @@ public:
override
{
if (change.m_old_state == m_sm.get_start_state ()
- && unchecked_p (change.m_new_state))
+ && (unchecked_p (change.m_new_state) || nonnull_p (change.m_new_state)))
// TODO: verify that it's the allocation stmt, not a copy
return label_text::borrow ("allocated here");
if (unchecked_p (change.m_old_state)
@@ -1910,11 +1910,16 @@ malloc_state_machine::on_stmt (sm_context *sm_ctxt,
return true;
}
- if (is_named_call_p (callee_fndecl, "operator new", call, 1))
- on_allocator_call (sm_ctxt, call, &m_scalar_delete);
- else if (is_named_call_p (callee_fndecl, "operator new []", call, 1))
- on_allocator_call (sm_ctxt, call, &m_vector_delete);
- else if (is_named_call_p (callee_fndecl, "operator delete", call, 1)
+ if (!is_placement_new_p (call))
+ {
+ bool returns_nonnull = !TREE_NOTHROW (callee_fndecl) && flag_exceptions;
+ if (is_named_call_p (callee_fndecl, "operator new"))
+ on_allocator_call (sm_ctxt, call, &m_scalar_delete, returns_nonnull);
+ else if (is_named_call_p (callee_fndecl, "operator new []"))
+ on_allocator_call (sm_ctxt, call, &m_vector_delete, returns_nonnull);
+ }
+
+ if (is_named_call_p (callee_fndecl, "operator delete", call, 1)
|| is_named_call_p (callee_fndecl, "operator delete", call, 2))
{
on_deallocator_call (sm_ctxt, node, call,
diff --git a/gcc/testsuite/g++.dg/analyzer/new-2.C
b/gcc/testsuite/g++.dg/analyzer/new-2.C
new file mode 100644
index 00000000000..4e696040a54
--- /dev/null
+++ b/gcc/testsuite/g++.dg/analyzer/new-2.C
@@ -0,0 +1,50 @@
+// { dg-additional-options "-O0" }
+
+struct A
+{
+ int x;
+ int y;
+};
+
+void test_spurious_null_warning_throwing ()
+{
+ int *x = new int; /* { dg-bogus "dereference of possibly-NULL" } */
+ int *y = new int (); /* { dg-bogus "dereference of possibly-NULL"
"non-throwing" } */
+ int *arr = new int[3]; /* { dg-bogus "dereference of possibly-NULL" } */
+ A *a = new A (); /* { dg-bogus "dereference of possibly-NULL" "throwing new
cannot be null" } */
+
+ int z = *y + 2;
+ z = *x + 4; /* { dg-bogus "dereference of possibly-NULL 'x'" } */
+ /* { dg-warning "use of uninitialized value '\\*x'" "" { target *-*-* } .-1
} */
+ z = arr[0] + 4; /* { dg-bogus "dereference of possibly-NULL" } */
+
+ delete a;
+ delete y;
+ delete x;
+ delete[] arr;
+}
+
+void test_default_initialization ()
+{
+ int *y = ::new int;
+ int *x = ::new int (); /* { dg-bogus "dereference of possibly-NULL
'operator new" } */
+
+ int b = *x + 3; /* { dg-bogus "dereference of possibly-NULL" } */
+ /* { dg-bogus "use of uninitialized ‘*x’" "" { target *-*-* } .-1 } */
+ int a = *y + 2; /* { dg-bogus "dereference of possibly-NULL 'y'" } */
+ /* { dg-warning "use of uninitialized value '\\*y'" "no default init" {
target *-*-* } .-1 } */
+
+ delete x;
+ delete y;
+}
+
+/* From clang core.uninitialized.NewArraySize
+new[] should not be called with an undefined size argument */
+
+void test_garbage_new_array ()
+{
+ int n;
+ int *arr = ::new int[n]; /* { dg-warning "use of uninitialized value 'n'" }
*/
+ arr[0] = 7;
+ ::delete[] arr; /* no warnings emitted here either */
+}
diff --git a/gcc/testsuite/g++.dg/analyzer/noexcept-new.C
b/gcc/testsuite/g++.dg/analyzer/noexcept-new.C
new file mode 100644
index 00000000000..7699cd99cff
--- /dev/null
+++ b/gcc/testsuite/g++.dg/analyzer/noexcept-new.C
@@ -0,0 +1,48 @@
+/* { dg-additional-options "-O0 -fno-exceptions
-fno-analyzer-suppress-followups" } */
+#include <new>
+
+/* Test non-throwing variants of operator new */
+
+struct A
+{
+ int x;
+ int y;
+};
+
+void test_throwing ()
+{
+ int* x = new int;
+ int* y = new int(); /* { dg-warning "dereference of possibly-NULL" } */
+ int* arr = new int[10];
+ A *a = new A(); /* { dg-warning "dereference of possibly-NULL" } */
+
+ int z = *y + 2;
+ z = *x + 4; /* { dg-warning "dereference of possibly-NULL 'x'" } */
+ /* { dg-warning "use of uninitialized value '\\*x'" "" { target *-*-* } .-1
} */
+ z = arr[0] + 4; /* { dg-warning "dereference of possibly-NULL 'arr'" } */
+ /* { dg-warning "use of uninitialized value '\\*arr'" "" { target *-*-* }
.-1 } */
+ a->y = a->x + 3;
+
+ delete a;
+ delete y;
+ delete x;
+ delete[] arr;
+}
+
+void test_nonthrowing ()
+{
+ int* x = new(std::nothrow) int;
+ int* y = new(std::nothrow) int();
+ int* arr = new(std::nothrow) int[10];
+
+ int z = *y + 2; /* { dg-warning "dereference of NULL 'y'" } */
+ /* { dg-warning "use of uninitialized value '\\*y'" "" { target *-*-* } .-1
} */
+ z = *x + 4; /* { dg-warning "dereference of possibly-NULL 'x'" } */
+ /* { dg-warning "use of uninitialized value '\\*x'" "" { target *-*-* } .-1
} */
+ z = arr[0] + 4; /* { dg-warning "dereference of possibly-NULL 'arr'" } */
+ /* { dg-warning "use of uninitialized value '\\*arr'" "" { target *-*-* }
.-1 } */
+
+ delete y;
+ delete x;
+ delete[] arr;
+}
diff --git a/gcc/testsuite/g++.dg/analyzer/out-of-bounds-placement-new.C
b/gcc/testsuite/g++.dg/analyzer/out-of-bounds-placement-new.C
index d3076c3cf25..33872e6ddab 100644
--- a/gcc/testsuite/g++.dg/analyzer/out-of-bounds-placement-new.C
+++ b/gcc/testsuite/g++.dg/analyzer/out-of-bounds-placement-new.C
@@ -14,6 +14,6 @@ struct int_and_addr {
int test (int_container ic)
{
- int_and_addr *iaddr = new (ic.addr ()) int_and_addr;
+ int_and_addr *iaddr = new (ic.addr ()) int_and_addr; /* { dg-warning
"stack-based buffer overflow" } */
return iaddr->i;
}
diff --git a/gcc/testsuite/g++.dg/analyzer/placement-new-size.C
b/gcc/testsuite/g++.dg/analyzer/placement-new-size.C
new file mode 100644
index 00000000000..4536d361b4a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/analyzer/placement-new-size.C
@@ -0,0 +1,27 @@
+/* { dg-additional-options "-Wno-placement-new
-Wno-analyzer-use-of-uninitialized-value" } */
+
+#include <new>
+#include <stdint.h>
+
+extern int get_buf_size ();
+
+void var_too_short ()
+{
+ int8_t s;
+ int64_t *lp = new (&s) int64_t; /* { dg-warning "stack-based buffer
overflow" } */
+ /* { dg-warning "allocated buffer size is not a multiple of the pointee's
size" "" { target *-*-* } .-1 } */
+}
+
+void static_buffer_too_short ()
+{
+ int n = 16;
+ int buf[n];
+ int *p = new (buf) int[n + 1]; /* { dg-warning "stack-based buffer overflow"
} */
+}
+
+void symbolic_buffer_too_short ()
+{
+ int n = get_buf_size ();
+ char buf[n];
+ char *p = new (buf) char[n + 10]; /* { dg-warning "stack-based buffer
overflow" } */
+}
diff --git a/gcc/testsuite/g++.dg/analyzer/placement-new.C
b/gcc/testsuite/g++.dg/analyzer/placement-new.C
index 89055491a48..c0cf7ec4c48 100644
--- a/gcc/testsuite/g++.dg/analyzer/placement-new.C
+++ b/gcc/testsuite/g++.dg/analyzer/placement-new.C
@@ -14,15 +14,74 @@ void test_2 (void)
{
char buf[sizeof(int) * 10];
int *p = new(buf) int[10];
-}
+} // { dg-prune-output "-Wfree-nonheap-object" }
/* Delete of placement new. */
void test_3 (void)
{
char buf[sizeof(int)]; // { dg-message "region created on stack here" }
- int *p = new(buf) int (42);
+ int *p = new (buf) int (42);
delete p; // { dg-warning "memory on the stack" }
}
// { dg-prune-output "-Wfree-nonheap-object" }
+
+void test_4 (void)
+{
+ int buf[5]; // { dg-message "region created on stack here" }
+ int *p = new (&buf[2]) int (42);
+ delete p; // { dg-warning "memory on the stack" }
+}
+
+
+// { dg-prune-output "-Wfree-nonheap-object" }
+
+void test_write_placement_after_delete (void)
+{
+ short *s = ::new short;
+ short *lp = ::new (s) short;
+ ::delete s;
+ *lp = 12; /* { dg-warning "use after 'delete' of 'lp'" "write placement new
after buffer deletion" } */
+}
+
+void test_read_placement_after_delete (void)
+{
+ short *s = ::new short;
+ short *lp = ::new (s) short;
+ ::delete s;
+ short m = *lp; // { dg-warning "use after 'delete' of 'lp'" "read placement
new after buffer deletion" }
+}
+
+struct A
+{
+ int x;
+ int y;
+};
+
+void test_use_placement_after_destruction (void)
+{
+ A a;
+ int *lp = ::new (&a.y) int;
+ *lp = 2; /* { dg-bogus "-Wanalyzer-use-of-uninitialized-value" } */
+ a.~A();
+ int m = *lp; /* { dg-warning "use of uninitialized value '\\*lp'" "use of
placement after the underlying buffer was destructed." } */
+}
+
+void test_initialization_through_placement (void)
+{
+ int x;
+ int *p = ::new (&x) int;
+ *p = 10;
+ int z = x + 2; /* { dg-bogus "use of uninitialized value 'x'" "x has been
initialized through placement pointer" } */
+}
+
+void test_partial_initialization_through_placement (void)
+{
+ char buf[4];
+ char *p = ::new (&buf[2]) char;
+ *p = 10;
+ char *y = ::new (&buf[0]) char;
+ char z = buf[2] + 2; /* { dg-bogus "use of uninitialized value" } */
+ z = *y + 2; /* { dg-warning "use of uninitialized value '\\*y'" "y has only
been partially initialized" } */
+}
\ No newline at end of file
--
2.34.1
