Messages in this thread Patch in this message | | | From | Rusty Russell <> | Date | Sun, 19 Oct 2008 22:18:50 -0500 | Subject | [PATCH 1/5] 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> --- include/linux/module.h | 2 +- include/linux/moduleparam.h | 6 +++++- kernel/params.c | 7 ++----- 3 files changed, 8 insertions(+), 7 deletions(-)
diff -r 87bd0f4cec3a include/linux/module.h --- a/include/linux/module.h Wed Aug 27 14:23:25 2008 +1000 +++ b/include/linux/module.h Wed Aug 27 21:00:10 2008 +1000 @@ -28,7 +28,7 @@ #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 -r 87bd0f4cec3a include/linux/moduleparam.h --- a/include/linux/moduleparam.h Wed Aug 27 14:23:25 2008 +1000 +++ b/include/linux/moduleparam.h Wed Aug 27 21:00:10 2008 +1000 @@ -12,6 +12,9 @@ #else #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 @@ -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 -r 87bd0f4cec3a kernel/params.c --- a/kernel/params.c Wed Aug 27 14:23:25 2008 +1000 +++ b/kernel/params.c Wed Aug 27 21:00:10 2008 +1000 @@ -585,17 +585,14 @@ static void __init param_sysfs_builtin(v { 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);
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