Fix IPMI watchdog set_param_str() using kstrdup

Fix IPMI watchdog set_param_str() using kstrdup

[Sébastien Dugué]

  I've wondered for some time why my IPMI watchdog stopped working. I traced it
back to the following patch:

	[PATCH] ipmi: strstrip conversion

  Here is a patch to fix this issue.

  Sébastien.


                Fix IPMI watchdog set_param_str() using kstrdup

  set_param_str() cannot use kstrdup() to duplicate the parameter. That's
fine when the driver is compiled as a module but it sure is not when
built into the kernel as the kernel parameters are parsed before the
kmalloc slabs are setup.


 ipmi_watchdog.c |   11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

Signed-off-by: Sébastien Dugué <sebastien.dugue@bull.net>

Index: linux-2.6.20-rc1/drivers/char/ipmi/ipmi_watchdog.c
===================================================================
--- linux-2.6.20-rc1.orig/drivers/char/ipmi/ipmi_watchdog.c	2006-12-14 02:14:23.000000000 +0100
+++ linux-2.6.20-rc1/drivers/char/ipmi/ipmi_watchdog.c	2006-12-19 17:20:06.000000000 +0100
@@ -216,13 +216,13 @@ static int set_param_str(const char *val
 {
 	action_fn  fn = (action_fn) kp->arg;
 	int        rv = 0;
-	char       *dup, *s;
+	char       valcp[16];
+	char       *s;
 
-	dup = kstrdup(val, GFP_KERNEL);
-	if (!dup)
-		return -ENOMEM;
+	strncpy(valcp, val, 16);
+	valcp[15] = '\0';
 
-	s = strstrip(dup);
+	s = strstrip(valcp);
 
 	down_read(&register_sem);
 	rv = fn(s, NULL);
@@ -235,7 +235,6 @@ static int set_param_str(const char *val
 
  out_unlock:
 	up_read(&register_sem);
-	kfree(dup);
 	return rv;
 }
 

Re: Fix IPMI watchdog set_param_str() using kstrdup

[Pekka Enberg]

On 12/20/06, Sébastien Dugué <sebastien.dugue@bull.net> wrote:
>   set_param_str() cannot use kstrdup() to duplicate the parameter. That's
> fine when the driver is compiled as a module but it sure is not when
> built into the kernel as the kernel parameters are parsed before the
> kmalloc slabs are setup.

Aah. I wonder though, if we could defer parsing driver parameters
until kmalloc caches are up...

Re: Fix IPMI watchdog set_param_str() using kstrdup

[Sébastien Dugué]

On Wed, 20 Dec 2006 13:19:09 +0200 "Pekka Enberg" <penberg@cs.helsinki.fi> wrote:

> On 12/20/06, Sébastien Dugué <sebastien.dugue@bull.net> wrote:
> >   set_param_str() cannot use kstrdup() to duplicate the parameter. That's
> > fine when the driver is compiled as a module but it sure is not when
> > built into the kernel as the kernel parameters are parsed before the
> > kmalloc slabs are setup.
> 
> Aah. I wonder though, if we could defer parsing driver parameters
> until kmalloc caches are up...

  From a general point of view, why not. Except that for the
watchdog case, I want it to start as soon as possible for it to be
able to reboot in case of an early crash.

  Sébastien.