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authorFrederic Weisbecker <fweisbec@gmail.com>2008-10-22 19:14:55 +0200
committerIngo Molnar <mingo@elte.hu>2008-10-27 16:45:46 +0100
commitf66af459a931f25807e1df7915b2b66bb5978d82 (patch)
treebb88917429fe1ea4f6d6e088ead040b25d205a86 /kernel
parent5209f08dc8e5f520ca81b87fa9a7142f58a109f4 (diff)
downloadlinux-f66af459a931f25807e1df7915b2b66bb5978d82.tar.gz
tracepoint: check if the probe has been registered
Impact: fix kernel crash that can trigger during tracing

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>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/tracepoint.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index f2b7c28a4708..af8c85664882 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);