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From: Dongdong Deng on 22 Feb 2010 05:40
The param_set_fn() function will get a parameter which is a NULL
pointer when insmod module via bare params as following method:

$insmod foo.ko foo

If the param_set_fn() function didn't check that parameter and used
it directly, it could caused an OOPS due to NULL pointer dereference.

The solution is simple:
Using "" to replace NULL parameter, thereby the param_set_fn()
function will never get a NULL pointer.

Signed-off-by: Dongdong Deng <dongdong.deng(a)windriver.com>
---
kernel/params.c | 30 ++++++------------------------
1 files changed, 6 insertions(+), 24 deletions(-)

diff --git a/kernel/params.c b/kernel/params.c
index cf1b691..548d680 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -101,7 +101,11 @@ static char *next_arg(char *args, char **param, char **val)

*param = args;
if (!equals)
- *val = NULL;
+ /*
+ * We used to hand NULL for bare params, but most code
+ * didn't handle it. Using "" to replace NULL here.
+ */
+ *val = "";
else {
args[equals] = '\0';
*val = args + equals + 1;
@@ -180,10 +184,7 @@ int parse_args(const char *name,
int param_set_##name(const char *val, struct kernel_param *kp) \
{ \
tmptype l; \
- int ret; \
- \
- if (!val) return -EINVAL; \
- ret = strtolfn(val, 0, &l); \
+ int ret = strtolfn(val, 0, &l); \
if (ret == -EINVAL || ((type)l != l)) \
return -EINVAL; \
*((type *)kp->arg) = l; \
@@ -204,12 +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);
@@ -238,9 +233,6 @@ int param_set_bool(const char *val, struct kernel_param *kp)
{
bool v;

- /* No equals means "set"... */
- if (!val) val = "1";
-
/* One of =[yYnN01] */
switch (val[0]) {
case 'y': case 'Y': case '1':
@@ -310,12 +302,6 @@ 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 {
@@ -382,10 +368,6 @@ 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);
--
1.6.0.4

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Prev: hw-breakpoint regression fixes
Next: x86: Enable NMI on all cpus on UV