From 730b69d225259565c705f5f5a11cb1aba69568f1 Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Wed, 22 Oct 2008 10:00:22 -0500
Subject: [PATCH] module: check kernel param length at compile time, not
runtime
The kparam code tries to handle over-length parameter prefixes at
runtime. Not only would I bet this has never been tested, it's not
clear that truncating names is a good idea either.
So let's check at compile time. We need to move the #define to
moduleparam.h to do this, though.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
include/linux/module.h | 2 +-
include/linux/moduleparam.h | 6 +++++-
kernel/params.c | 7 ++-----
3 files changed, 8 insertions(+), 7 deletions(-)
diff --git a/include/linux/module.h b/include/linux/module.h
index eddf27db442b..196b499270da 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -29,7 +29,7 @@
#define MODULE_SYMBOL_PREFIX ""
#endif
-#define MODULE_NAME_LEN (64 - sizeof(unsigned long))
+#define MODULE_NAME_LEN MAX_PARAM_PREFIX_LEN
struct kernel_symbol
{
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index ec624381c844..1eefe6d61b86 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -13,6 +13,9 @@
#define MODULE_PARAM_PREFIX KBUILD_MODNAME "."
#endif
+/* Chosen so that structs with an unsigned long line up. */
+#define MAX_PARAM_PREFIX_LEN (64 - sizeof(unsigned long))
+
#ifdef MODULE
#define ___module_cat(a,b) __mod_ ## a ## b
#define __module_cat(a,b) ___module_cat(a,b)
@@ -79,7 +82,8 @@ struct kparam_array
#define __module_param_call(prefix, name, set, get, arg, perm) \
/* Default value instead of permissions? */ \
static int __param_perm_check_##name __attribute__((unused)) = \
- BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2)); \
+ BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2)) \
+ + BUILD_BUG_ON_ZERO(sizeof(""prefix) > MAX_PARAM_PREFIX_LEN); \
static const char __param_str_##name[] = prefix #name; \
static struct kernel_param __moduleparam_const __param_##name \
__used \
diff --git a/kernel/params.c b/kernel/params.c
index afc46a23eb6d..aca07e1a050f 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -585,17 +585,14 @@ static void __init param_sysfs_builtin(void)
{
struct kernel_param *kp, *kp_begin = NULL;
unsigned int i, name_len, count = 0;
- char modname[MODULE_NAME_LEN + 1] = "";
+ char modname[MODULE_NAME_LEN] = "";
for (i=0; i < __stop___param - __start___param; i++) {
char *dot;
- size_t max_name_len;
kp = &__start___param[i];
- max_name_len =
- min_t(size_t, MODULE_NAME_LEN, strlen(kp->name));
- dot = memchr(kp->name, '.', max_name_len);
+ dot = strchr(kp->name, '.');
if (!dot) {
DEBUGP("couldn't find period in first %d characters "
"of %s\n", MODULE_NAME_LEN, kp->name);