lkml.org 
[lkml]   [2015]   [Mar]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC][PATCH 1/9] klp: Fix obvious RCU fail
On Sat, Feb 28, 2015 at 10:24:48PM +0100, Peter Zijlstra wrote:
> While one must hold RCU-sched (aka. preempt_disable) for find_symbol()
> one must equally hold it over the use of the object returned.
>
> The moment you release the RCU-sched read lock, the object can be dead
> and gone.
>
> Cc: Seth Jennings <sjenning@redhat.com>
> Cc: Josh Poimboeuf <jpoimboe@redhat.com>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Cc: Miroslav Benes <mbenes@suse.cz>
> Cc: Petr Mladek <pmladek@suse.cz>
> Cc: Jiri Kosina <jkosina@suse.cz>
> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
> Cc: Rusty Russell <rusty@rustcorp.com.au>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>

> ---
> kernel/livepatch/core.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> --- a/kernel/livepatch/core.c
> +++ b/kernel/livepatch/core.c
> @@ -248,11 +248,12 @@ static int klp_find_external_symbol(stru
> /* first, check if it's an exported symbol */
> preempt_disable();
> sym = find_symbol(name, NULL, NULL, true, true);
> - preempt_enable();
> if (sym) {
> *addr = sym->value;
> + preempt_enable();
> return 0;
> }
> + preempt_enable();
>
> /* otherwise check if it's in another .o within the patch module */
> return klp_find_object_symbol(pmod->name, name, addr);
>
>

--
Josh


\
 
 \ /
  Last update: 2015-03-02 22:21    [W:0.232 / U:0.244 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site