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

Frederic Weisbecker

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Oct 10, 2008, 7:20:11 AM10/10/08

to

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 <fwei...@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);

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Ingo Molnar

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Oct 10, 2008, 10:10:08 AM10/10/08

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* Frederic Weisbecker <fwei...@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 <fwei...@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

Mathieu Desnoyers

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Oct 10, 2008, 11:50:10 AM10/10/08

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* Ingo Molnar (mi...@elte.hu) wrote:
>
> * Frederic Weisbecker <fwei...@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 <fwei...@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....@polymtl.ca>

Mathieu

> Ingo

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

Steven Rostedt

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Oct 10, 2008, 1:00:17 PM10/10/08

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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 <sros...@redhat.com>

-- Steve

Steven Rostedt

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Oct 10, 2008, 1:00:15 PM10/10/08

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On Fri, 10 Oct 2008, Ingo Molnar wrote:

>
> * Frederic Weisbecker <fwei...@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 <fwei...@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

Frédéric Weisbecker

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Oct 13, 2008, 6:00:22 AM10/13/08

to

2008/10/10 Ingo Molnar <mi...@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....

Ingo Molnar

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Oct 27, 2008, 12:20:21 PM10/27/08

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

> 2008/10/10 Ingo Molnar <mi...@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