linux-kernel - Re: [patch v2 4/4] ptrace: Add support for generic PTRACE_GETREGSET/PTRACE

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:	Wed, 10 Feb 2010 18:17:03 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Roland McGrath <roland@...hat.com>
CC:	Oleg Nesterov <oleg@...hat.com>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>, hjl.tools@...il.com
Subject: Re: [patch v2 4/4] ptrace: Add support for generic	PTRACE_GETREGSET/PTRACE_SETREGSET

On 02/10/2010 11:12 AM, Roland McGrath wrote:
> 
> Since it's just two words, most places handling struct iovec seem to just
> use two get_user() calls, which is probably more efficient.
> 
> Also, here is where this function would need to be split in half for
> compat_ptrace_request() calls where it has to use struct compat_iovec.
> 
>> +	// I am not sure. Afaics it is OK to pass the
>> +	// size which is less than n * size. If iov_len
>> +	// is bigger, we can silently truncate it, or
>> +	// even write the correct value back.
> 
> Modifying iov_len to report how much we accessed seems good to me.  If we
> do that, we should certainly allow a larger size for get, so userland can
> just use a generic large buffer before even knowing the real size.  I'm not
> sure whether we should allow a smaller size, especially for set.  I could
> go either way.
> 

Allowing a larger size for get seems very sane.  Allowing a smaller size
would be ok iff we make sure we handle corner cases right (i.e. a
partially overwritten subregister.)

	-hpa
--
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/