linux-kernel - [PATCH v5 02/21] x86, KASLR: Handle kernel relocation above 2G

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1460672954-32567-3-git-send-email-keescook@chromium.org>
Date:	Thu, 14 Apr 2016 15:28:55 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Kees Cook <keescook@...omium.org>, Baoquan He <bhe@...hat.com>,
	Yinghai Lu <yinghai@...nel.org>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Matt Redfearn <matt.redfearn@...tec.com>, x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Vivek Goyal <vgoyal@...hat.com>,
	Andy Lutomirski <luto@...nel.org>, lasse.collin@...aani.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dave Young <dyoung@...hat.com>,
	kernel-hardening@...ts.openwall.com,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH v5 02/21] x86, KASLR: Handle kernel relocation above 2G

From: Baoquan He <bhe@...hat.com>

When processing the relocation table, the offset used to calculate the
relocation is an int. This is sufficient for calculating the physical
address of the relocs entry on 32-bit systems and on 64-bit systems when
the relocation is under 2G. To handle relocations above 2G (seen in
situations like kexec, netboot, etc), this offset needs to be calculated
using a long to avoid wrapping and miscalculating the relocation.

Signed-off-by: Baoquan He <bhe@...hat.com>
[kees: rewrote changelog]
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 arch/x86/boot/compressed/misc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index f35ad9eb1bf1..c4477d5f3fff 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -295,7 +295,7 @@ static void handle_relocations(void *output, unsigned long output_len)
 	 * So we work backwards from the end of the decompressed image.
 	 */
 	for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
-		int extended = *reloc;
+		long extended = *reloc;
 		extended += map;
 
 		ptr = (unsigned long)extended;
-- 
2.6.3