params: don't hand NULL values to param.set callbacks.
Rusty Russell [Thu, 12 Aug 2010 05:04:10 +0000 (23:04 -0600)]
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>

kernel/params.c

index 0b30ecd..3c4a9f1 100644 (file)
@@ -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);