perf: Validate cpu early in perf_event_alloc()

66832eb4 · Oleg Nesterov <[email protected]> · 2011-01-18 17:10:32 +01:00

Starting from perf_event_alloc()->perf_init_event(), the kernel
assumes that event->cpu is either -1 or the valid CPU number.

Change perf_event_alloc() to validate this argument early. This
also means we can remove the similar check in
find_get_context().

Signed-off-by: Oleg Nesterov <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Cc: Alan Stern <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Prasad <[email protected]>
Cc: Roland McGrath <[email protected]>
Cc: [email protected]
Cc: [email protected]
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

Commit: 66832eb4baaaa9abe4c993ddf9113a79e39b9915
Parents: 22a4ec72

Changes

1 files changed · +6 −4

File	Status	Add	Del	Content
kernel/perf_event.c	modified	+6	−4	View file

kernel/perf_event.c

View file

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index a962b19..67d9bd7 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -2233,9 +2233,6 @@ find_get_context(struct pmu *pmu, struct task_struct *task, int cpu)
 		if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
 			return ERR_PTR(-EACCES);
 
-		if (cpu < 0 || cpu >= nr_cpumask_bits)
-			return ERR_PTR(-EINVAL);
-
 		/*
 		 * We could be clever and allow to attach a event to an
 		 * offline CPU and activate it when the CPU comes up, but
@@ -5541,6 +5538,11 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
 	struct hw_perf_event *hwc;
 	long err;
 
+	if ((unsigned)cpu >= nr_cpu_ids) {
+		if (!task || cpu != -1)
+			return ERR_PTR(-EINVAL);
+	}
+
 	event = kzalloc(sizeof(*event), GFP_KERNEL);
 	if (!event)
 		return ERR_PTR(-ENOMEM);
@@ -5589,7 +5591,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
 
 	if (!overflow_handler && parent_event)
 		overflow_handler = parent_event->overflow_handler;
-	
+
 	event->overflow_handler	= overflow_handler;
 
 	if (attr->disabled)