linux-kernel - [PATCH 1/2] x86, microcode: Do Intel microcode revision check signed

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Message-Id: <1386363843-32530-1-git-send-email-andi@firstfloor.org>
Date:	Fri,  6 Dec 2013 13:04:02 -0800
From:	Andi Kleen <andi@...stfloor.org>
To:	linux-kernel@...r.kernel.org
Cc:	x86@...nel.org, Andi Kleen <ak@...ux.intel.com>
Subject: [PATCH 1/2] x86, microcode: Do Intel microcode revision check signed

From: Andi Kleen <ak@...ux.intel.com>

The Intel SDM Vol 3 9.11.1 Microcode update states that
the update revision field is signed. However we do the comparison
unsigned, as the comparison gets promoted.

Use a cast to really do a signed comparison of the microcode
revision.

Signed-off-by: Andi Kleen <ak@...ux.intel.com>
---
 arch/x86/kernel/microcode_intel_lib.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/microcode_intel_lib.c b/arch/x86/kernel/microcode_intel_lib.c
index ce69320..68503d1 100644
--- a/arch/x86/kernel/microcode_intel_lib.c
+++ b/arch/x86/kernel/microcode_intel_lib.c
@@ -41,7 +41,7 @@ update_match_cpu(unsigned int csig, unsigned int cpf,
 int
 update_match_revision(struct microcode_header_intel *mc_header, int rev)
 {
-	return (mc_header->rev <= rev) ? 0 : 1;
+	return ((int)mc_header->rev <= rev) ? 0 : 1;
 }
 
 int microcode_sanity_check(void *mc, int print_err)
-- 
1.8.3.1

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