* [patch 2/9] fs: Add missing rcu protection for __task_cred() in sys_ioprio_get
[not found] <20091210001308.247025548@linutronix.de>
@ 2009-12-10 0:52 ` Thomas Gleixner
2009-12-11 13:46 ` David Howells
1 sibling, 0 replies; 2+ messages in thread
From: Thomas Gleixner @ 2009-12-10 0:52 UTC (permalink / raw)
To: LKML
Cc: Paul E. McKenney, Dipankar Sarma, Ingo Molnar, Peter Zijlstra,
Oleg Nesterov, Al Viro, James Morris, David Howells,
Andrew Morton, Linus Torvalds, linux-security-module,
linux-fsdevel
[-- Attachment #1: fs-fix-missing-rcu-protection-of-__task_cred.patch --]
[-- Type: text/plain, Size: 1112 bytes --]
sys_ioprio_get() accesses __task_cred() without being in a RCU read
side critical section. tasklist_lock is not protecting that when
CONFIG_TREE_PREEMPT_RCU=y.
Add a rcu_read_lock/unlock() section around the code which accesses
__task_cred().
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: linux-security-module@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: Al Viro <viro@zeniv.linux.org.uk>
---
fs/ioprio.c | 2 ++
1 file changed, 2 insertions(+)
Index: linux-2.6-tip/fs/ioprio.c
===================================================================
--- linux-2.6-tip.orig/fs/ioprio.c
+++ linux-2.6-tip/fs/ioprio.c
@@ -230,6 +230,7 @@ SYSCALL_DEFINE2(ioprio_get, int, which,
if (!user)
break;
+ rcu_read_lock();
do_each_thread(g, p) {
if (__task_cred(p)->uid != user->uid)
continue;
@@ -241,6 +242,7 @@ SYSCALL_DEFINE2(ioprio_get, int, which,
else
ret = ioprio_best(ret, tmpio);
} while_each_thread(g, p);
+ rcu_read_unlock();
if (who)
free_uid(user);
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: [patch 2/9] fs: Add missing rcu protection for __task_cred() in sys_ioprio_get
[not found] <20091210001308.247025548@linutronix.de>
2009-12-10 0:52 ` [patch 2/9] fs: Add missing rcu protection for __task_cred() in sys_ioprio_get Thomas Gleixner
@ 2009-12-11 13:46 ` David Howells
1 sibling, 0 replies; 2+ messages in thread
From: David Howells @ 2009-12-11 13:46 UTC (permalink / raw)
To: Thomas Gleixner
Cc: dhowells, LKML, Paul E. McKenney, Dipankar Sarma, Ingo Molnar,
Peter Zijlstra, Oleg Nesterov, Al Viro, James Morris,
Andrew Morton, Linus Torvalds, linux-security-module,
linux-fsdevel
Thomas Gleixner <tglx@linutronix.de> wrote:
> sys_ioprio_get() accesses __task_cred() without being in a RCU read
> side critical section. tasklist_lock is not protecting that when
> CONFIG_TREE_PREEMPT_RCU=y.
>
> Add a rcu_read_lock/unlock() section around the code which accesses
> __task_cred().
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: David Howells <dhowells@redhat.com>
^ permalink raw reply [flat|nested] 2+ messages in thread