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 Cc: David Howells Cc: James Morris Cc: linux-security-module@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org Cc: Al Viro --- 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); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/