params: don't hand NULL values to param.set callbacks.

An audit by Dongdong Deng revealed that most driver-author-written param
calls don't handle val == NULL (which happens when parameters are specified
with no =, eg "foo" instead of "foo=1").

The only real case to use this is boolean, so handle it specially for that
case and remove a source of bugs for everyone else.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dongdong Deng <dongdong.deng@windriver.com>
Cc: Américo Wang <xiyou.wangcong@gmail.com>

1 files changed, 3 insertions, 17 deletions

diff --git a/kernel/params.c b/kernel/params.c
index 0b30ecd53a52..3c4a9f1b095e 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -58,6 +58,9 @@ static int parse_one(char *param,
         /* Find parameter */
         for (i = 0; i < num_params; i++) {
                 if (parameq(param, params[i].name)) {
+                        /* Noone handled NULL, so do it here. */
+                        if (!val && params[i].set != param_set_bool)
+                                return -EINVAL;
                         DEBUGP("They are equal!  Calling %p\n",
                                params[i].set);
                         return params[i].set(val, &params[i]);
@@ -181,7 +184,6 @@ int parse_args(const char *name,
                 tmptype l;                                              \
                 int ret;                                                \
                                                                         \
-                if (!val) return -EINVAL;                               \
                 ret = strtolfn(val, 0, &l);                             \
                 if (ret == -EINVAL || ((type)l != l))                   \
                         return -EINVAL;                                 \
@@ -203,12 +205,6 @@ STANDARD_PARAM_DEF(ulong, unsigned long, "%lu", unsigned long, strict_strtoul);
 
 int param_set_charp(const char *val, struct kernel_param *kp)
 {
-        if (!val) {
-                printk(KERN_ERR "%s: string parameter expected\n",
-                       kp->name);
-                return -EINVAL;
-        }
-
         if (strlen(val) > 1024) {
                 printk(KERN_ERR "%s: string parameter too long\n",
                        kp->name);
@@ -309,12 +305,6 @@ static int param_array(const char *name,
         kp.arg = elem;
         kp.flags = flags;
 
-        /* No equals sign? */
-        if (!val) {
-                printk(KERN_ERR "%s: expects arguments\n", name);
-                return -EINVAL;
-        }
-
         *num = 0;
         /* We expect a comma-separated list of values. */
         do {
@@ -381,10 +371,6 @@ int param_set_copystring(const char *val, struct kernel_param *kp)
 {
         const struct kparam_string *kps = kp->str;
 
-        if (!val) {
-                printk(KERN_ERR "%s: missing param set value\n", kp->name);
-                return -EINVAL;
-        }
         if (strlen(val)+1 > kps->maxlen) {
                 printk(KERN_ERR "%s: string doesn't fit in %u chars.\n",
                        kp->name, kps->maxlen-1);