linux-kernel - [tip:perf/urgent] perf: Validate cpu early in perf_event

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Message-ID: <tip-66832eb4baaaa9abe4c993ddf9113a79e39b9915@git.kernel.org>
Date:	Tue, 18 Jan 2011 19:07:23 GMT
From:	tip-bot for Oleg Nesterov <oleg@...hat.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, paulus@...ba.org, acme@...hat.com,
	hpa@...or.com, mingo@...hat.com, stern@...land.harvard.edu,
	a.p.zijlstra@...llo.nl, roland@...hat.com, fweisbec@...il.com,
	tglx@...utronix.de, oleg@...hat.com, mingo@...e.hu,
	prasad@...ux.vnet.ibm.com
Subject: [tip:perf/urgent] perf: Validate cpu early in perf_event_alloc()

Commit-ID:  66832eb4baaaa9abe4c993ddf9113a79e39b9915
Gitweb:     http://git.kernel.org/tip/66832eb4baaaa9abe4c993ddf9113a79e39b9915
Author:     Oleg Nesterov <oleg@...hat.com>
AuthorDate: Tue, 18 Jan 2011 17:10:32 +0100
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Tue, 18 Jan 2011 19:34:23 +0100

perf: Validate cpu early in perf_event_alloc()

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 <oleg@...hat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Alan Stern <stern@...land.harvard.edu>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Prasad <prasad@...ux.vnet.ibm.com>
Cc: Roland McGrath <roland@...hat.com>
Cc: gregkh@...e.de
Cc: stable@...nel.org
LKML-Reference: <20110118161032.GC693@...hat.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 kernel/perf_event.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)

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)
--
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