From: Chuck Lever <chuck.lever@oracle.com>
To: "Finney, Sean" <Sean.Finney@sonyericsson.com>
Cc: "rees@umich.edu" <rees@umich.edu>,
"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
"bfields@fieldses.org" <bfields@fieldses.org>
Subject: Re: [PATCH v2 1/2] nfs-utils: mountd: Use a dynamic buffer for storing lists of gid's
Date: Thu, 7 Apr 2011 10:29:39 -0400 [thread overview]
Message-ID: <5964B39E-ADFD-496C-98BE-D77920239E1B@oracle.com> (raw)
In-Reply-To: <A50602A820F61543B29992A418BB321B66E18F8A5E@seldmbx01.corpusers.net>
On Apr 7, 2011, at 10:15 AM, Finney, Sean wrote:
> Hi Jim,
>
> On Thu, 2011-04-07 at 08:22 -0400, Jim Rees wrote:
>
>> I was going to suggest you first call getgrouplist with groups set to 0 so
>> you can always alloc() the correct size list, but then I found this in the
>> man page:
>>
>> BUGS
>> In glibc versions before 2.3.3, the implementation of this function
>> contains a buffer-overrun bug: it returns the complete list of groups
>> for user in the array groups, even when the number of groups exceeds
>> *ngroups.
>
> Yuck. The function is also not in POSIX or any other standards, so
> maybe it's worth discussing at a later point whether getgroups(2) would
> be a better interface to use, even if it means an extra step or two.
The standard RPC library function authunix_create_default() uses getgroups(2). Take a look at the glibc version of this function to see the preferred method for using getgroups(2).
--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com
next prev parent reply other threads:[~2011-04-07 14:29 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-04 8:02 Fixes for NFS in environments with large group memberships Finney, Sean
[not found] ` <A50602A820F61543B29992A418BB321B66E18F8A4A-g6SuDuYnGwoBLpZRX7oUTsm4BeyDBExM@public.gmane.org>
2011-04-05 23:35 ` J. Bruce Fields
2011-04-07 5:53 ` Finney, Sean
2011-04-07 7:22 ` [PATCH v2 1/2] nfs-utils: mountd: Use a dynamic buffer for storing lists of gid's Sean Finney
2011-04-07 7:22 ` [PATCH v2 2/2] nfs-utils: Increase the stdio file buffer size for procfs files Sean Finney
2011-04-07 12:22 ` [PATCH v2 1/2] nfs-utils: mountd: Use a dynamic buffer for storing lists of gid's Jim Rees
2011-04-07 14:15 ` Finney, Sean
2011-04-07 14:29 ` Chuck Lever [this message]
2011-04-07 15:01 ` Jim Rees
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