[patch 3/9] proc: Add missing rcu protection for __task_cred() in task_sig()

Thomas Gleixner
2009-12-10T00:54:16Z

[-- Attachment #1: proc-fix-missing-rcu-protection-of-__task_cred.patch --]
[-- Type: text/plain, Size: 1074 bytes --]

task_sig() 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: Al Viro <viro@zeniv.linux.org.uk>

---
fs/proc/array.c | 2 ++
1 file changed, 2 insertions(+)

Index: linux-2.6-tip/fs/proc/array.c
===================================================================
--- linux-2.6-tip.orig/fs/proc/array.c
+++ linux-2.6-tip/fs/proc/array.c
@@ -265,7 +265,9 @@ static inline void task_sig(struct seq_f
blocked = p->blocked;
collect_sigign_sigcatch(p, &ignored, &caught);
num_threads = atomic_read(&p->signal->count);
+ rcu_read_lock();
qsize = atomic_read(&__task_cred(p)->user->sigpending);
+ rcu_read_unlock();
qlim = p->signal->rlim[RLIMIT_SIGPENDING].rlim_cur;
unlock_task_sighand(p, &flags);
}