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| author | Oleg Nesterov <oleg@redhat.com> | 2012-05-31 16:26:16 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-05-31 17:49:28 -0700 |
| commit | 43e13cc107cf6cd3c15fbe1cef849435c2223d50 (patch) | |
| tree | 9a1b3aa79ec2e8374944c23cf57a73790a3fc6ce /kernel/exit.c | |
| parent | 9b3c98cd663750c33434572ff76ba306505eba5a (diff) | |
| download | lwn-43e13cc107cf6cd3c15fbe1cef849435c2223d50.tar.gz lwn-43e13cc107cf6cd3c15fbe1cef849435c2223d50.zip | |
cred: remove task_is_dead() from __task_cred() validation
Commit 8f92054e7ca1 ("CRED: Fix __task_cred()'s lockdep check and banner
comment"):
add the following validation condition:
task->exit_state >= 0
to permit the access if the target task is dead and therefore
unable to change its own credentials.
OK, but afaics currently this can only help wait_task_zombie() which calls
__task_cred() without rcu lock.
Remove this validation and change wait_task_zombie() to use task_uid()
instead. This means we do rcu_read_lock() only to shut up the lockdep,
but we already do the same in, say, wait_task_stopped().
task_is_dead() should die, task->exit_state != 0 means that this task has
passed exit_notify(), only do_wait-like code paths should use this.
Unfortunately, we can't kill task_is_dead() right now, it has already
acquired buggy users in drivers/staging. The fix already exists.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: David Howells <dhowells@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/exit.c')
| -rw-r--r-- | kernel/exit.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index 910a0716e17a..3281493ce7ad 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1214,7 +1214,7 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) unsigned long state; int retval, status, traced; pid_t pid = task_pid_vnr(p); - uid_t uid = from_kuid_munged(current_user_ns(), __task_cred(p)->uid); + uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p)); struct siginfo __user *infop; if (!likely(wo->wo_flags & WEXITED)) |