lkml.org 
[lkml]   [2015]   [Apr]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] lsm: copy comm before calling audit_log to avoid race in string printing
On Tue, 14 Apr 2015, Richard Guy Briggs wrote:

> When task->comm is passed directly to audit_log_untrustedstring() without
> getting a copy or using the task_lock, there is a race that could happen that
> would output a NULL (\0) in the middle of the output string that would
> effectively truncate the rest of the report text after the comm= field in the
> audit log message, losing fields.
>
> Using get_task_comm() to get a copy while acquiring the task_lock to prevent
> this and to prevent the result from being a mixture of old and new values of
> comm would incur potentially unacceptable overhead, considering that the value
> can be influenced by userspace and therefore untrusted anyways.
>
> Copy the value before passing it to audit_log_untrustedstring() ensures that a
> local copy is used to calculate the length *and* subsequently printed. Even if
> this value contains a mix of old and new values, it will only calculate and
> copy up to the first NULL, preventing the rest of the audit log message being
> truncated.
>
> Use a second local copy of comm to avoid a race between the first and second
> calls to audit_log_untrustedstring() with comm.
>
> Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> Signed-off-by: Richard Guy Briggs <rgb@redhat.com>

Applied.

--
James Morris
<jmorris@namei.org>



\
 
 \ /
  Last update: 2015-04-15 02:01    [W:0.034 / U:0.504 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site