diff options
| author | Davidlohr Bueso <davidlohr.bueso@hp.com> | 2013-07-08 16:01:12 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-10-18 07:45:46 -0700 |
| commit | ac9bc6e396285ab732dd869c3edb353662134022 (patch) | |
| tree | 182b0be2e0238d96e02c8669e372c254d6ea81a1 /ipc/msg.c | |
| parent | 115d40dbef93b70e6f32732b0fdd5903c1f7fce4 (diff) | |
ipc: move locking out of ipcctl_pre_down_nolock
commit 7b4cc5d8411bd4e9d61d8714f53859740cf830c2 upstream.
This function currently acquires both the rw_mutex and the rcu lock on
successful lookups, leaving the callers to explicitly unlock them,
creating another two level locking situation.
Make the callers (including those that still use ipcctl_pre_down())
explicitly lock and unlock the rwsem and rcu lock.
Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'ipc/msg.c')
| -rw-r--r-- | ipc/msg.c | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/ipc/msg.c b/ipc/msg.c index 56bff33457b2..6c1609d572cc 100644 --- a/ipc/msg.c +++ b/ipc/msg.c @@ -407,31 +407,38 @@ static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd, return -EFAULT; } + down_write(&msg_ids(ns).rw_mutex); + rcu_read_lock(); + ipcp = ipcctl_pre_down(ns, &msg_ids(ns), msqid, cmd, &msqid64.msg_perm, msqid64.msg_qbytes); - if (IS_ERR(ipcp)) - return PTR_ERR(ipcp); + if (IS_ERR(ipcp)) { + err = PTR_ERR(ipcp); + /* the ipc lock is not held upon failure */ + goto out_unlock1; + } msq = container_of(ipcp, struct msg_queue, q_perm); err = security_msg_queue_msgctl(msq, cmd); if (err) - goto out_unlock; + goto out_unlock0; switch (cmd) { case IPC_RMID: + /* freeque unlocks the ipc object and rcu */ freeque(ns, ipcp); goto out_up; case IPC_SET: if (msqid64.msg_qbytes > ns->msg_ctlmnb && !capable(CAP_SYS_RESOURCE)) { err = -EPERM; - goto out_unlock; + goto out_unlock0; } err = ipc_update_perm(&msqid64.msg_perm, ipcp); if (err) - goto out_unlock; + goto out_unlock0; msq->q_qbytes = msqid64.msg_qbytes; @@ -448,8 +455,11 @@ static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd, default: err = -EINVAL; } -out_unlock: - msg_unlock(msq); + +out_unlock0: + ipc_unlock_object(&msq->q_perm); +out_unlock1: + rcu_read_unlock(); out_up: up_write(&msg_ids(ns).rw_mutex); return err; |