[3.19.y-ckt stable] Patch "x86/mpx: Fix off-by-one comparison with nr_registers" has been added to the 3.19.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    x86/mpx: Fix off-by-one comparison with nr_registers

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt16.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From 121528357971d5e7b5cbd4395c8c73f90e4d52cb Mon Sep 17 00:00:00 2001
From: Colin Ian King <colin.king at canonical.com>
Date: Fri, 26 Feb 2016 18:55:31 +0000
Subject: x86/mpx: Fix off-by-one comparison with nr_registers

commit 9bf148cb0812595bfdf5100bd2c07e9bec9c6ef5 upstream.

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.

Fixes: fcc7ffd67991 "x86, mpx: Decode MPX instruction to get bound violation information"
Signed-off-by: Colin Ian King <colin.king at canonical.com>
Acked-by: Dave Hansen <dave.hansen at linux.intel.com>
Cc: Borislav Petkov <bp at alien8.de>
Cc: "Kirill A . Shutemov" <kirill.shutemov at linux.intel.com>
Link: http://lkml.kernel.org/r/1456512931-3388-1-git-send-email-colin.king@canonical.com
Signed-off-by: Thomas Gleixner <tglx at linutronix.de>
Signed-off-by: Kamal Mostafa <kamal at 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 feda8ca..0b0382a 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -142,7 +142,7 @@ 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