[PATCH 2/6] tracepoint: Check if the probe has been registered

[PATCH 2/6] tracepoint: Check if the probe has been registered

[Frederic Weisbecker]

If we try to remove a probe that has not been already registered,
the tracepoint_entry_remove_probe() function will dereference a NULL
pointer.
Check the probe before removing it to avoid crashes.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 kernel/tracepoint.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index f2b7c28..af8c856 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -131,6 +131,9 @@ tracepoint_entry_remove_probe(struct tracepoint_entry *entry, void *probe)
 
 	old = entry->funcs;
 
+	if (!old)
+		return NULL;
+
 	debug_print_probes(entry);
 	/* (N -> M), (N > 1, M >= 0) probes */
 	for (nr_probes = 0; old[nr_probes]; nr_probes++) {
@@ -388,6 +391,11 @@ int tracepoint_probe_unregister(const char *name, void *probe)
 	if (entry->rcu_pending)
 		rcu_barrier_sched();
 	old = tracepoint_entry_remove_probe(entry, probe);
+	if (!old) {
+		printk(KERN_WARNING "Warning: Trying to unregister a probe"
+				    "that doesn't exist\n");
+		goto end;
+	}
 	mutex_unlock(&tracepoints_mutex);
 	tracepoint_update_probes();		/* may update entry */
 	mutex_lock(&tracepoints_mutex);

Re: [PATCH 2/6] tracepoint: Check if the probe has been registered

[Ingo Molnar]

* Frederic Weisbecker <fweisbec@gmail.com> wrote:

> If we try to remove a probe that has not been already registered, the 
> tracepoint_entry_remove_probe() function will dereference a NULL 
> pointer. Check the probe before removing it to avoid crashes.
> 
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> ---
>  kernel/tracepoint.c |    8 ++++++++
>  1 files changed, 8 insertions(+), 0 deletions(-)

applied to tip/tracing/tracepoints, thanks Frederic!

Mathieu, Steve, any objections/observations?

	Ingo

Re: [PATCH 2/6] tracepoint: Check if the probe has been registered

[Mathieu Desnoyers]

* Ingo Molnar (mingo@elte.hu) wrote:
> 
> * Frederic Weisbecker <fweisbec@gmail.com> wrote:
> 
> > If we try to remove a probe that has not been already registered, the 
> > tracepoint_entry_remove_probe() function will dereference a NULL 
> > pointer. Check the probe before removing it to avoid crashes.
> > 
> > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> > ---
> >  kernel/tracepoint.c |    8 ++++++++
> >  1 files changed, 8 insertions(+), 0 deletions(-)
> 
> applied to tip/tracing/tracepoints, thanks Frederic!
> 
> Mathieu, Steve, any objections/observations?
> 

Looks good to me. Thanks !

Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

Mathieu

> 	Ingo

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

Re: [PATCH 2/6] tracepoint: Check if the probe has been registered

[Steven Rostedt]

On Fri, 10 Oct 2008, Ingo Molnar wrote:

> 
> * Frederic Weisbecker <fweisbec@gmail.com> wrote:
> 
> > If we try to remove a probe that has not been already registered, the 
> > tracepoint_entry_remove_probe() function will dereference a NULL 
> > pointer. Check the probe before removing it to avoid crashes.
> > 
> > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> > ---
> >  kernel/tracepoint.c |    8 ++++++++
> >  1 files changed, 8 insertions(+), 0 deletions(-)
> 
> applied to tip/tracing/tracepoints, thanks Frederic!
> 
> Mathieu, Steve, any objections/observations?

Hmm, my email was on the fritz for this one. I'll have to search for it on 
a mailing list web site to see the patch.

-- Steve

Re: [PATCH 2/6] tracepoint: Check if the probe has been registered

[Steven Rostedt]

On Fri, 10 Oct 2008, Steven Rostedt wrote:
> > 
> > Mathieu, Steve, any objections/observations?
> 
> Hmm, my email was on the fritz for this one. I'll have to search for it on 
> a mailing list web site to see the patch.


OK, found it at 
http://groups.google.com/group/linux.kernel/browse_thread/thread/9519141803211fee/70a273bb6a1ea602?lnk=raot

Looks good for me too.

Acked-by: Steven Rostedt <srostedt@redhat.com>

-- Steve

Re: [PATCH 2/6] tracepoint: Check if the probe has been registered

[Frédéric Weisbecker]

2008/10/10 Ingo Molnar <mingo@elte.hu>:
> applied to tip/tracing/tracepoints, thanks Frederic!

Hi Ingo.

Are you sure it has been applied? It seems to be lost in the sea :)

Thanks....

Re: [PATCH 2/6] tracepoint: Check if the probe has been registered

[Ingo Molnar]

* Frédéric Weisbecker <fweisbec@gmail.com> wrote:

> 2008/10/10 Ingo Molnar <mingo@elte.hu>:
> > applied to tip/tracing/tracepoints, thanks Frederic!
> 
> Hi Ingo.
> 
> Are you sure it has been applied? It seems to be lost in the sea :)
> 
> Thanks....

should be this one:

f66af45: tracepoint: check if the probe has been registered

	Ingo