From: Colin Ian King <colin.king@canonical.com>
Date: Thu, 16 Jul 2020 14:38:56 +0000 (+0100)
Subject: refperf: Avoid null pointer dereference when buf fails to allocate
X-Git-Tag: v5.9.2~351
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=7db67e4c4bfa21d29cfade3337217b94543eaa82;p=users%2Fdwmw2%2Flinux.git

refperf: Avoid null pointer dereference when buf fails to allocate

[ Upstream commit 58db5785b0d76be4582a32a7900acce88e691d36 ]

Currently in the unlikely event that buf fails to be allocated it
is dereferenced a few times.  Use the errexit flag to determine if
buf should be written to to avoid the null pointer dereferences.

Addresses-Coverity: ("Dereference after null check")
Fixes: f518f154ecef ("refperf: Dynamically allocate experiment-summary output buffer")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c
index d9291f883b542..952595c678b37 100644
--- a/kernel/rcu/refscale.c
+++ b/kernel/rcu/refscale.c
@@ -546,9 +546,11 @@ static int main_func(void *arg)
 	// Print the average of all experiments
 	SCALEOUT("END OF TEST. Calculating average duration per loop (nanoseconds)...\n");
 
-	buf[0] = 0;
-	strcat(buf, "\n");
-	strcat(buf, "Runs\tTime(ns)\n");
+	if (!errexit) {
+		buf[0] = 0;
+		strcat(buf, "\n");
+		strcat(buf, "Runs\tTime(ns)\n");
+	}
 
 	for (exp = 0; exp < nruns; exp++) {
 		u64 avg;