From: Frederic Weisbecker Date: Wed, 22 Oct 2008 17:14:55 +0000 (+0200) Subject: tracepoint: check if the probe has been registered X-Git-Tag: firefly_0821_release~17071^2~4 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=f66af459a931f25807e1df7915b2b66bb5978d82;p=firefly-linux-kernel-4.4.55.git 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 Acked-by: Mathieu Desnoyers Acked-by: Steven Rostedt Signed-off-by: Ingo Molnar --- 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);