From: David Howells <dhowells@redhat.com>
To: Edwin van Vliet <edwin@cheatah.nl>
Cc: dhowells@redhat.com, akpm@linux-foundation.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kernel/cred: Fix bug on cred reference count
Date: Sat, 09 Jul 2011 10:13:47 +0100 [thread overview]
Message-ID: <10155.1310202827@redhat.com> (raw)
In-Reply-To: <1310194141-18700-1-git-send-email-edwin@cheatah.nl>
Edwin van Vliet <edwin@cheatah.nl> wrote:
> The comment above states that the old obj ref and subj ref should BOTH be
> released. However, the line is repeated so the old obj ref is released twice
> yet the subj ref is not. So either the comment is wrong, or this is simpy a
> bug. Releasing the same ref twice seems wrong in any case.
The comment is correct and the double release is correct.
task_struct has *two* refs to the cred being replaced and both need to be
updated:
current->real_cred - The objective cred
current->cred - The subjective cred
The subjective cred is the one used by a task to access other objects; the
objective cred details how the task is perceived by the outside world and
affects how other tasks act upon it.
Normally a task's two cred pointers point to the same cred, but under some
circumstances (such as in cachefiles), the subjective cred can be overridden.
David
prev parent reply other threads:[~2011-07-09 9:14 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-09 6:49 [PATCH] kernel/cred: Fix bug on cred reference count Edwin van Vliet
2011-07-09 9:13 ` David Howells [this message]
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