gcc/c-family/ChangeLog:
PR C/108896
* c-ubsan.cc (ubsan_instrument_bounds): Use counted_by attribute
information.
gcc/testsuite/ChangeLog:
PR C/108896
* gcc.dg/ubsan/flex-array-counted-by-bounds.c: New test.
* gcc.dg/ubsan/flex-array-counted-by-bounds-2.c: New test.
---
gcc/c-family/c-ubsan.cc | 16 +++++++
.../ubsan/flex-array-counted-by-bounds-2.c | 27 +++++++++++
.../ubsan/flex-array-counted-by-bounds.c | 46 +++++++++++++++++++
3 files changed, 89 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/ubsan/flex-array-counted-by-bounds-2.c
create mode 100644 gcc/testsuite/gcc.dg/ubsan/flex-array-counted-by-bounds.c
diff --git a/gcc/c-family/c-ubsan.cc b/gcc/c-family/c-ubsan.cc
index 51aa83a378d2..a99e8433069f 100644
--- a/gcc/c-family/c-ubsan.cc
+++ b/gcc/c-family/c-ubsan.cc
@@ -362,6 +362,10 @@ ubsan_instrument_bounds (location_t loc, tree array, tree
*index,
{
tree type = TREE_TYPE (array);
tree domain = TYPE_DOMAIN (type);
+ /* whether the array ref is a flexible array member with valid counted_by
+ attribute. */
+ bool fam_has_count_attr = false;
+ tree counted_by = NULL_TREE;
if (domain == NULL_TREE)
return NULL_TREE;
@@ -375,6 +379,17 @@ ubsan_instrument_bounds (location_t loc, tree array, tree
*index,
&& COMPLETE_TYPE_P (type)
&& integer_zerop (TYPE_SIZE (type)))
bound = build_int_cst (TREE_TYPE (TYPE_MIN_VALUE (domain)), -1);
+ /* If the array ref is to flexible array member field which has
+ counted_by attribute. We can use the information from the
+ attribute as the bound to instrument the reference. */
+ else if ((counted_by = component_ref_get_counted_by (array))
+ != NULL_TREE)
+ {
+ fam_has_count_attr = true;
+ bound = fold_build2 (MINUS_EXPR, TREE_TYPE (counted_by),
+ counted_by,
+ build_int_cst (TREE_TYPE (counted_by), 1));
+ }
else
return NULL_TREE;
}
@@ -387,6 +402,7 @@ ubsan_instrument_bounds (location_t loc, tree array, tree
*index,
-fsanitize=bounds-strict. */
tree base = get_base_address (array);
if (!sanitize_flags_p (SANITIZE_BOUNDS_STRICT)
+ && !fam_has_count_attr
&& TREE_CODE (array) == COMPONENT_REF
&& base && (INDIRECT_REF_P (base) || TREE_CODE (base) == MEM_REF))
{
diff --git a/gcc/testsuite/gcc.dg/ubsan/flex-array-counted-by-bounds-2.c
b/gcc/testsuite/gcc.dg/ubsan/flex-array-counted-by-bounds-2.c
new file mode 100644
index 000000000000..77ec333509d0
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/ubsan/flex-array-counted-by-bounds-2.c
@@ -0,0 +1,27 @@
+/* test the attribute counted_by and its usage in
+ bounds sanitizer combined with VLA. */
+/* { dg-do run } */
+/* { dg-options "-fsanitize=bounds" } */
+
+#include <stdlib.h>
+
+void __attribute__((__noinline__)) setup_and_test_vla (int n, int m)
+{
+ struct foo {
+ int n;
+ int p[][n] __attribute__((counted_by(n)));
+ } *f;
+
+ f = (struct foo *) malloc (sizeof(struct foo) + m*sizeof(int[n]));
+ f->n = m;
+ f->p[m][n-1]=1;
+ return;
+}
+
+int main(int argc, char *argv[])
+{
+ setup_and_test_vla (10, 11);
+ return 0;
+}
+
+/* { dg-output "17:8: runtime error: index 11 out of bounds for type" } */
diff --git a/gcc/testsuite/gcc.dg/ubsan/flex-array-counted-by-bounds.c
b/gcc/testsuite/gcc.dg/ubsan/flex-array-counted-by-bounds.c
new file mode 100644
index 000000000000..81eaeb3f2681
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/ubsan/flex-array-counted-by-bounds.c
@@ -0,0 +1,46 @@
+/* test the attribute counted_by and its usage in
+ bounds sanitizer. */
+/* { dg-do run } */
+/* { dg-options "-fsanitize=bounds" } */
+
+#include <stdlib.h>
+
+struct flex {
+ int b;
+ int c[];
+} *array_flex;
+
+struct annotated {
+ int b;
+ int c[] __attribute__ ((counted_by (b)));
+} *array_annotated;
+
+void __attribute__((__noinline__)) setup (int normal_count, int
annotated_count)
+{
+ array_flex
+ = (struct flex *)malloc (sizeof (struct flex)
+ + normal_count * sizeof (int));
+ array_flex->b = normal_count;
+
+ array_annotated
+ = (struct annotated *)malloc (sizeof (struct annotated)
+ + annotated_count * sizeof (int));
+ array_annotated->b = annotated_count;
+
+ return;
+}
+
+void __attribute__((__noinline__)) test (int normal_index, int annotated_index)
+{
+ array_flex->c[normal_index] = 1;
+ array_annotated->c[annotated_index] = 2;
+}
+
+int main(int argc, char *argv[])
+{
+ setup (10, 10);
+ test (10, 10);
+ return 0;
+}
+
+/* { dg-output "36:21: runtime error: index 10 out of bounds for type" } */
--
2.31.1
