linux-kernel - [PATCH tip/core/rcu 2/6] rcutorture: Check nfakewriters parameter

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Message-Id: <1437176737-26668-2-git-send-email-paulmck@linux.vnet.ibm.com>
Date:	Fri, 17 Jul 2015 16:45:33 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
	akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
	josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
	rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
	dvhart@...ux.intel.com, fweisbec@...il.com, oleg@...hat.com,
	bobby.prani@...il.com,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 2/6] rcutorture: Check nfakewriters parameter

From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>

Currently, a negative value for rcutorture.nfakewriters= can cause
rcutorture to pass a negative size to the memory allocator, which
is not really a particularly good thing to do.  This commit therefore
adds bounds checking to this parameter, so that values that are less
than or equal to zero disable fake writing.

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 kernel/rcu/rcutorture.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 7e29a3266139..2cbe569ac5dd 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1786,12 +1786,15 @@ rcu_torture_init(void)
 					  writer_task);
 	if (firsterr)
 		goto unwind;
-	fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
-				   GFP_KERNEL);
-	if (fakewriter_tasks == NULL) {
-		VERBOSE_TOROUT_ERRSTRING("out of memory");
-		firsterr = -ENOMEM;
-		goto unwind;
+	if (nfakewriters > 0) {
+		fakewriter_tasks = kzalloc(nfakewriters *
+					   sizeof(fakewriter_tasks[0]),
+					   GFP_KERNEL);
+		if (fakewriter_tasks == NULL) {
+			VERBOSE_TOROUT_ERRSTRING("out of memory");
+			firsterr = -ENOMEM;
+			goto unwind;
+		}
 	}
 	for (i = 0; i < nfakewriters; i++) {
 		firsterr = torture_create_kthread(rcu_torture_fakewriter,
-- 
1.8.1.5

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