lib/string_helpers: annotate struct strarray with __counted_by_ptr

Add the __counted_by_ptr() compiler attribute to 'array' to improve
bounds checking via CONFIG_UBSAN_BOUNDS and CONFIG_FORTIFY_SOURCE.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Link: https://patch.msgid.link/20260415122542.370926-6-thorsten.blum@linux.dev
Signed-off-by: Kees Cook <kees@kernel.org>

diff --git a/lib/string_helpers.c b/lib/string_helpers.c
index 6a8db441b6fd173f87098e5b466c64397642e6dd..98d6ed0eaab7e9f3d54e420c404629a28b925bf4 100644 (file)
--- a/lib/string_helpers.c
+++ b/lib/string_helpers.c
@@ -805,7 +805,7 @@ void kfree_strarray(char **array, size_t n)
 EXPORT_SYMBOL_GPL(kfree_strarray);
 
 struct strarray {
-       char **array;
+       char **array __counted_by_ptr(n);
        size_t n;
 };
 
@@ -824,13 +824,13 @@ char **devm_kasprintf_strarray(struct device *dev, const char *prefix, size_t n)
        if (!ptr)
                return ERR_PTR(-ENOMEM);
 
+       ptr->n = n;
        ptr->array = kasprintf_strarray(GFP_KERNEL, prefix, n);
        if (!ptr->array) {
                devres_free(ptr);
                return ERR_PTR(-ENOMEM);
        }
 
-       ptr->n = n;
        devres_add(dev, ptr);
 
        return ptr->array;