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module: check kernel param length at compile time, not runtime

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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>
This commit is contained in:
Rusty Russell 2008-10-22 10:00:22 -05:00
parent d72b37513c
commit 730b69d225
3 changed files with 8 additions and 7 deletions
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2
include/linux/module.h
View file

@ -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
{

6
include/linux/moduleparam.h
View file

@ -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 \

7
kernel/params.c
View file

@ -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);