linux-kernel - Re: [PATCH] arm: fix integer overflow in ELF_ET_DYN

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]

Date:	Thu, 26 Mar 2015 15:05:58 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Andrey Ryabinin <a.ryabinin@...sung.com>
Cc:	Kees Cook <keescook@...omium.org>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Maria Guseva <m.guseva@...sung.com>,
	Yury Gribov <y.gribov@...sung.com>, stable@...r.kernel.org
Subject: Re: [PATCH] arm: fix integer overflow in ELF_ET_DYN_BASE

On Fri, Mar 20, 2015 at 02:12:52PM +0300, Andrey Ryabinin wrote:
> Usually ELF_ET_DYN_BASE is 2/3 of TASK_SIZE. With 3G/1G user/kernel
> split this is not so, because 2*TASK_SIZE overflows 32 bits,
> so the actual value of ELF_ET_DYN_BASE is:
> 	(2 * TASK_SIZE / 3) = 0x2a000000
> 
> When ASLR is disabled PIE binaries will load at ELF_ET_DYN_BASE address.
> On 32bit platforms AddressSanitzer uses addresses [0x20000000 - 0x40000000]
> for shadow memory [1]. So ASan doesn't work for PIE binaries when ASLR disabled
> as it fails to map shadow memory.
> Also after Kees's 'split ET_DYN ASLR from mmap ASLR' patchset PIE binaries
> has a high chance of loading somewhere in between [0x2a000000 - 0x40000000]
> even if ASLR enabled. This makes ASan with PIE absolutely incompatible.
> 
> Fix overflow by dividing TASK_SIZE prior to multiplying.
> After this patch ELF_ET_DYN_BASE equals to (for CONFIG_VMSPLIT_3G=y):
> 	(TASK_SIZE / 3 * 2) = 0x7f555554
> 
> [1] https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm#Mapping
> 
> Signed-off-by: Andrey Ryabinin <a.ryabinin@...sung.com>
> Reported-by: Maria Guseva <m.guseva@...sung.com>
> Cc: stable@...r.kernel.org

Who's handling this patch?  I'm guessing it should be me, so if it could
find its way into my patch system for when I next apply a bunch of patches,
that'd be good.

Thanks.

-- 
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/