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From: Kees Cook <keescook@chromium.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>,
	Yinghai Lu <yinghai@kernel.org>, Baoquan He <bhe@redhat.com>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Borislav Petkov <bp@alien8.de>, Vivek Goyal <vgoyal@redhat.com>,
	Andy Lutomirski <luto@kernel.org>,
	lasse.collin@tukaani.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Dave Young <dyoung@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH 6/6] x86/boot: Correctly bounds-check relocations
Date: Thu, 28 Apr 2016 17:09:08 -0700
Message-ID: <1461888548-32439-7-git-send-email-keescook@chromium.org> (raw)
In-Reply-To: <1461888548-32439-1-git-send-email-keescook@chromium.org>

From: Yinghai Lu <yinghai@kernel.org>

Relocation handling performs bounds checking on the resulting calculated
addresses. The existing code uses output_len (VO size plus relocs size) as
the max address. This is not right since the max_addr check should stop at
the end of VO and exclude bss, brk, etc, which follows.  The valid range
should be VO [_text, __bss_start] in the loaded physical address space.

This patch adds an export for __bss_start in voffset.h and uses it to
set the correct limit for max_addr.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
[kees: rewrote changelog]
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 arch/x86/boot/compressed/Makefile | 2 +-
 arch/x86/boot/compressed/misc.c   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index adef26d22224..75f2233b8414 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -57,7 +57,7 @@ LDFLAGS_vmlinux := -T
 hostprogs-y	:= mkpiggy
 HOST_EXTRACFLAGS += -I$(srctree)/tools/include
 
-sed-voffset := -e 's/^\([0-9a-fA-F]*\) [ABCDGRSTVW] \(_text\|_end\)$$/\#define VO_\2 _AC(0x\1,UL)/p'
+sed-voffset := -e 's/^\([0-9a-fA-F]*\) [ABCDGRSTVW] \(_text\|__bss_start\|_end\)$$/\#define VO_\2 _AC(0x\1,UL)/p'
 
 quiet_cmd_voffset = VOFFSET $@
       cmd_voffset = $(NM) $< | sed -n $(sed-voffset) > $@
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index bee6238e7cfc..8f0253d8c7ff 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -191,7 +191,7 @@ static void handle_relocations(void *output, unsigned long output_len)
 	int *reloc;
 	unsigned long delta, map, ptr;
 	unsigned long min_addr = (unsigned long)output;
-	unsigned long max_addr = min_addr + output_len;
+	unsigned long max_addr = min_addr + (VO___bss_start - VO__text);
 
 	/*
 	 * Calculate the delta between where vmlinux was linked to load
-- 
2.6.3

  parent reply index

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-29  0:09 [PATCH 0/6] x86/boot: Improve compressed kernel handling Kees Cook
2016-04-29  0:09 ` [PATCH 1/6] x86/KASLR: Handle kernel relocation above 2G Kees Cook
2016-04-29  8:02   ` [tip:x86/boot] x86/KASLR: Handle kernel relocations above 2G correctly tip-bot for Baoquan He
2016-04-29  0:09 ` [PATCH 2/6] x86/boot: Move compressed kernel to end of decompression buffer Kees Cook
2016-04-29  7:18   ` Ingo Molnar
2016-04-29  7:48     ` Kees Cook
2016-04-29  8:07       ` Ingo Molnar
2016-04-29  9:51         ` Ingo Molnar
2016-04-29  9:51   ` [tip:x86/boot] x86/boot: Move compressed kernel to the end of the " tip-bot for Yinghai Lu
2016-08-16  4:01   ` [PATCH 2/6] x86/boot: Move compressed kernel to end of " Matt Mullins
2016-08-16 19:19     ` Yinghai Lu
2016-08-17  2:25       ` Matt Mullins
2016-10-03 21:50         ` Simon Glass
2016-11-30 16:52           ` Andy Shevchenko
2016-04-29  0:09 ` [PATCH 3/6] x86/boot: Calculate decompression size during boot not build Kees Cook
2016-04-29  9:52   ` [tip:x86/boot] " tip-bot for Yinghai Lu
2016-04-29  0:09 ` [PATCH 4/6] x86/boot: Fix "run_size" calculation Kees Cook
2016-04-29  9:52   ` [tip:x86/boot] " tip-bot for Yinghai Lu
2016-04-29  0:09 ` [PATCH 5/6] x86/KASLR: Clean up unused code from old "run_size" Kees Cook
2016-04-29  9:52   ` [tip:x86/boot] x86/KASLR: Clean up unused code from old 'run_size' and rename it to 'kernel_total_size' tip-bot for Yinghai Lu
2016-04-29  0:09 ` Kees Cook [this message]
2016-04-29  9:53   ` [tip:x86/boot] x86/boot: Correctly bounds-check relocations tip-bot for Yinghai Lu

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