linux-kernel - [PATCH AUTOSEL for 4.9 136/156] powerpc/perf/hv-24x7: Fix incorrect comparison in memord

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Message-ID: <20171207154845.4814-136-alexander.levin@verizon.com>
Date:   Thu, 7 Dec 2017 15:49:30 +0000
From:   alexander.levin@...izon.com
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Cc:     Michael Ellerman <mpe@...erman.id.au>, alexander.levin@...izon.com
Subject: [PATCH AUTOSEL for 4.9 136/156] powerpc/perf/hv-24x7: Fix incorrect
 comparison in memord

From: Michael Ellerman <mpe@...erman.id.au>

[ Upstream commit 05c14c03138532a3cb2aa29c2960445c8753343b ]

In the hv-24x7 code there is a function memord() which tries to
implement a sort function return -1, 0, 1. However one of the
conditions is incorrect, such that it can never be true, because we
will have already returned.

I don't believe there is a bug in practice though, because the
comparisons are an optimisation prior to calling memcmp().

Fix it by swapping the second comparision, so it can be true.

Reported-by: David Binderman <dcb314@...mail.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
---
 arch/powerpc/perf/hv-24x7.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/perf/hv-24x7.c b/arch/powerpc/perf/hv-24x7.c
index 7b2ca16b1eb4..991c6a517ddc 100644
--- a/arch/powerpc/perf/hv-24x7.c
+++ b/arch/powerpc/perf/hv-24x7.c
@@ -516,7 +516,7 @@ static int memord(const void *d1, size_t s1, const void *d2, size_t s2)
 {
 	if (s1 < s2)
 		return 1;
-	if (s2 > s1)
+	if (s1 > s2)
 		return -1;
 
 	return memcmp(d1, d2, s1);
-- 
2.11.0