lkdtm/fortify: Swap memcpy() for strncpy()

The memcpy() runtime defenses are still not landed, so test with
strncpy() for now.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reported-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220216202548.2093883-1-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/lkdtm/fortify.c b/drivers/misc/lkdtm/fortify.c
index d06458a4858e4aadd30c8072a49f9fde52a85ea4..ab33bb5e2e7afa245ced328eda8f501bb67bdd1f 100644 (file)
--- a/drivers/misc/lkdtm/fortify.c
+++ b/drivers/misc/lkdtm/fortify.c
@@ -44,14 +44,14 @@ void lkdtm_FORTIFIED_SUBOBJECT(void)
        strscpy(src, "over ten bytes", size);
        size = strlen(src) + 1;
 
-       pr_info("trying to strcpy past the end of a member of a struct\n");
+       pr_info("trying to strncpy past the end of a member of a struct\n");
 
        /*
-        * memcpy(target.a, src, 20); will hit a compile error because the
+        * strncpy(target.a, src, 20); will hit a compile error because the
         * compiler knows at build time that target.a < 20 bytes. Use a
         * volatile to force a runtime error.
         */
-       memcpy(target.a, src, size);
+       strncpy(target.a, src, size);
 
        /* Store result to global to prevent the code from being eliminated */
        fortify_scratch_space = target.a[3];