linux-kernel - Re: [PATCH v2] ARM: uaccess: Implement strict user copy checks

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:	Sat, 28 Aug 2010 11:56:56 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Heiko Carstens <heiko.carstens@...ibm.com>
Cc:	Stephen Boyd <sboyd@...eaurora.org>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Russell King <linux@....linux.org.uk>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2] ARM: uaccess: Implement strict user copy checks

On Saturday 28 August 2010 09:43:04 Heiko Carstens wrote:
> In function 'copy_from_user',
>     inlined from '__tun_chr_ioctl' at drivers/net/tun.c:1200:
> /linux-2.6/arch/s390/include/asm/uaccess.h:297: warning: call to 'copy_from_user_overflow' declared with attribute warning: copy_from_user() buffer size is not provably correct

I wrote this one, and I can't think of an easy way to do fix
it without increasing the code complexity or size.

> In function 'copy_from_user',
>     inlined from 'write_file_bool' at fs/debugfs/file.c:434:
> /linux-2.6/arch/s390/include/asm/uaccess.h:297: warning: call to 'copy_from_user_overflow' declared with attribute warning: copy_from_user() buffer size is not provably correct
> In function 'copy_from_user',
>     inlined from 'packet_getsockopt' at net/packet/af_packet.c:2123:
> /linux-2.6/arch/s390/include/asm/uaccess.h:297: warning: call to 'copy_from_user_overflow' declared with attribute warning: copy_from_user() buffer size is not provably correct

These look like the compiler is not smart enough. Both make sure
that we copy at most the size of the object, or less if the user
didn't pass all of it.

> In function 'copy_from_user',
>     inlined from 'compat_sys_socketcall' at net/compat.c:783:
> /linux-2.6/arch/s390/include/asm/uaccess.h:297: warning: call to 'copy_from_user_overflow' declared with attribute warning: copy_from_user() buffer size is not provably correct

I don't think the compiler has a chance to figure this one out.
However, I don't see the warning on x86. Maybe x86-gcc has
a bug.

	Arnd
--
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/