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From: Colin King <colin.king@canonical.com>
To: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>,
	"H . Peter Anvin" <hpa@linux.intel.com>,
	x86@kernel.org, Dave Hansen <dave.hansen@linux.intel.com>,
	Borislav Petkov <bp@alien8.de>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH] x86/mpx: Fix off-by-one comparison with nr_registers
Date: Fri, 26 Feb 2016 18:55:31 +0000
Message-ID: <1456512931-3388-1-git-send-email-colin.king@canonical.com> (raw)

From: Colin Ian King <colin.king@canonical.com>

In the unlikely event that regno == nr_registers then we get an array
overrun on regoff because the invalid register check is currently
off-by-one. Fix this with a check that regno is >= nr_registers instead.

Detected with static analysis using CoverityScan.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 arch/x86/mm/mpx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 5584397..8047687 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -123,7 +123,7 @@ static int get_reg_offset(struct insn *insn, struct pt_regs *regs,
 		break;
 	}
 
-	if (regno > nr_registers) {
+	if (regno >= nr_registers) {
 		WARN_ONCE(1, "decoded an instruction with an invalid register");
 		return -EINVAL;
 	}
-- 
2.7.0

             reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-26 18:55 Colin King [this message]
2016-02-26 19:08 ` Dave Hansen
2016-02-26 21:15 ` [tip:x86/urgent] " tip-bot for Colin Ian King

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