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authorFrederic Weisbecker <fweisbec@gmail.com>2008-10-22 13:14:55 -0400
committerIngo Molnar <mingo@elte.hu>2008-10-27 11:45:46 -0400
commitf66af459a931f25807e1df7915b2b66bb5978d82 (patch)
treebb88917429fe1ea4f6d6e088ead040b25d205a86
parent5209f08dc8e5f520ca81b87fa9a7142f58a109f4 (diff)
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>
-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)
131 131
132 old = entry->funcs; 132 old = entry->funcs;
133 133
134 if (!old)
135 return NULL;
136
134 debug_print_probes(entry); 137 debug_print_probes(entry);
135 /* (N -> M), (N > 1, M >= 0) probes */ 138 /* (N -> M), (N > 1, M >= 0) probes */
136 for (nr_probes = 0; old[nr_probes]; nr_probes++) { 139 for (nr_probes = 0; old[nr_probes]; nr_probes++) {
@@ -388,6 +391,11 @@ int tracepoint_probe_unregister(const char *name, void *probe)
388 if (entry->rcu_pending) 391 if (entry->rcu_pending)
389 rcu_barrier_sched(); 392 rcu_barrier_sched();
390 old = tracepoint_entry_remove_probe(entry, probe); 393 old = tracepoint_entry_remove_probe(entry, probe);
394 if (!old) {
395 printk(KERN_WARNING "Warning: Trying to unregister a probe"
396 "that doesn't exist\n");
397 goto end;
398 }
391 mutex_unlock(&tracepoints_mutex); 399 mutex_unlock(&tracepoints_mutex);
392 tracepoint_update_probes(); /* may update entry */ 400 tracepoint_update_probes(); /* may update entry */
393 mutex_lock(&tracepoints_mutex); 401 mutex_lock(&tracepoints_mutex);