linux-kernel - [tip:x86/mm] x86/kexec: Correct KEXEC_BACKUP_SRC

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Date:   Tue, 9 Oct 2018 08:30:50 -0700
From:   tip-bot for Bjorn Helgaas <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     lijiang@...hat.com, brijesh.singh@....com, tglx@...utronix.de,
        gregkh@...uxfoundation.org, thomas.lendacky@....com,
        mingo@...nel.org, akpm@...ux-foundation.org, hpa@...or.com,
        mingo@...hat.com, bp@...e.de, vgoyal@...hat.com, tiwai@...e.de,
        bhelgaas@...gle.com, linux-kernel@...r.kernel.org
Subject: [tip:x86/mm] x86/kexec: Correct KEXEC_BACKUP_SRC_END off-by-one
 error

Commit-ID:  51fbf14f2528a8c6401290e37f1c893a2412f1d3
Gitweb:     https://git.kernel.org/tip/51fbf14f2528a8c6401290e37f1c893a2412f1d3
Author:     Bjorn Helgaas <bhelgaas@...gle.com>
AuthorDate: Thu, 27 Sep 2018 09:21:55 -0500
Committer:  Borislav Petkov <bp@...e.de>
CommitDate: Tue, 9 Oct 2018 17:18:31 +0200

x86/kexec: Correct KEXEC_BACKUP_SRC_END off-by-one error

The only use of KEXEC_BACKUP_SRC_END is as an argument to
walk_system_ram_res():

  int crash_load_segments(struct kimage *image)
  {
    ...
    walk_system_ram_res(KEXEC_BACKUP_SRC_START, KEXEC_BACKUP_SRC_END,
                        image, determine_backup_region);

walk_system_ram_res() expects "start, end" arguments that are inclusive,
i.e., the range to be walked includes both the start and end addresses.

KEXEC_BACKUP_SRC_END was previously defined as (640 * 1024UL), which is the
first address *past* the desired 0-640KB range.

Define KEXEC_BACKUP_SRC_END as (640 * 1024UL - 1) so the KEXEC_BACKUP_SRC
region is [0-0x9ffff], not [0-0xa0000].

Fixes: dd5f726076cc ("kexec: support for kexec on panic using new system call")
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
CC: "H. Peter Anvin" <hpa@...or.com>
CC: Andrew Morton <akpm@...ux-foundation.org>
CC: Brijesh Singh <brijesh.singh@....com>
CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC: Ingo Molnar <mingo@...hat.com>
CC: Lianbo Jiang <lijiang@...hat.com>
CC: Takashi Iwai <tiwai@...e.de>
CC: Thomas Gleixner <tglx@...utronix.de>
CC: Tom Lendacky <thomas.lendacky@....com>
CC: Vivek Goyal <vgoyal@...hat.com>
CC: baiyaowei@...s.chinamobile.com
CC: bhe@...hat.com
CC: dan.j.williams@...el.com
CC: dyoung@...hat.com
CC: kexec@...ts.infradead.org
Link: http://lkml.kernel.org/r/153805811578.1157.6948388946904655969.stgit@bhelgaas-glaptop.roam.corp.google.com
---
 arch/x86/include/asm/kexec.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index f327236f0fa7..5125fca472bb 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -67,7 +67,7 @@ struct kimage;
 
 /* Memory to backup during crash kdump */
 #define KEXEC_BACKUP_SRC_START	(0UL)
-#define KEXEC_BACKUP_SRC_END	(640 * 1024UL)	/* 640K */
+#define KEXEC_BACKUP_SRC_END	(640 * 1024UL - 1)	/* 640K */
 
 /*
  * CPU does not save ss and sp on stack if execution is already