sysv, ipc: fix security-layer leaking

Commit 53dad6d3a8e5 ("ipc: fix race with LSMs") updated ipc_rcu_putref()
to receive rcu freeing function but used generic ipc_rcu_free() instead
of msg_rcu_free() which does security cleaning.

Running LTP msgsnd06 with kmemleak gives the following:

  cat /sys/kernel/debug/kmemleak

  unreferenced object 0xffff88003c0a11f8 (size 8):
    comm "msgsnd06", pid 1645, jiffies 4294672526 (age 6.549s)
    hex dump (first 8 bytes):
      1b 00 00 00 01 00 00 00                          ........
    backtrace:
      kmemleak_alloc+0x23/0x40
      kmem_cache_alloc_trace+0xe1/0x180
      selinux_msg_queue_alloc_security+0x3f/0xd0
      security_msg_queue_alloc+0x2e/0x40
      newque+0x4e/0x150
      ipcget+0x159/0x1b0
      SyS_msgget+0x39/0x40
      entry_SYSCALL_64_fastpath+0x13/0x8f

Manfred Spraul suggested to fix sem.c as well and Davidlohr Bueso to
only use ipc_rcu_free in case of security allocation failure in newary()

Fixes: 53dad6d3a8e ("ipc: fix race with LSMs")
Link: http://lkml.kernel.org/r/1470083552-22966-1-git-send-email-fabf@skynet.be
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: <stable@vger.kernel.org>	[3.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 7 insertions, 7 deletions

diff --git a/ipc/msg.c b/ipc/msg.c
index 1471db9a7e61..c6521c205cb4 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -680,7 +680,7 @@ long do_msgsnd(int msqid, long mtype, void __user *mtext,
                 rcu_read_lock();
                 ipc_lock_object(&msq->q_perm);
 
-                ipc_rcu_putref(msq, ipc_rcu_free);
+                ipc_rcu_putref(msq, msg_rcu_free);
                 /* raced with RMID? */
                 if (!ipc_valid_object(&msq->q_perm)) {
                         err = -EIDRM;
diff --git a/ipc/sem.c b/ipc/sem.c
index ae72b3cddc8d..7c9d4f7683c0 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -438,7 +438,7 @@ static inline struct sem_array *sem_obtain_object_check(struct ipc_namespace *ns
 static inline void sem_lock_and_putref(struct sem_array *sma)
 {
         sem_lock(sma, NULL, -1);
-        ipc_rcu_putref(sma, ipc_rcu_free);
+        ipc_rcu_putref(sma, sem_rcu_free);
 }
 
 static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s)
@@ -1381,7 +1381,7 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
                         rcu_read_unlock();
                         sem_io = ipc_alloc(sizeof(ushort)*nsems);
                         if (sem_io == NULL) {
-                                ipc_rcu_putref(sma, ipc_rcu_free);
+                                ipc_rcu_putref(sma, sem_rcu_free);
                                 return -ENOMEM;
                         }
 
@@ -1415,20 +1415,20 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
                 if (nsems > SEMMSL_FAST) {
                         sem_io = ipc_alloc(sizeof(ushort)*nsems);
                         if (sem_io == NULL) {
-                                ipc_rcu_putref(sma, ipc_rcu_free);
+                                ipc_rcu_putref(sma, sem_rcu_free);
                                 return -ENOMEM;
                         }
                 }
 
                 if (copy_from_user(sem_io, p, nsems*sizeof(ushort))) {
-                        ipc_rcu_putref(sma, ipc_rcu_free);
+                        ipc_rcu_putref(sma, sem_rcu_free);
                         err = -EFAULT;
                         goto out_free;
                 }
 
                 for (i = 0; i < nsems; i++) {
                         if (sem_io[i] > SEMVMX) {
-                                ipc_rcu_putref(sma, ipc_rcu_free);
+                                ipc_rcu_putref(sma, sem_rcu_free);
                                 err = -ERANGE;
                                 goto out_free;
                         }
@@ -1720,7 +1720,7 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid)
         /* step 2: allocate new undo structure */
         new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL);
         if (!new) {
-                ipc_rcu_putref(sma, ipc_rcu_free);
+                ipc_rcu_putref(sma, sem_rcu_free);
                 return ERR_PTR(-ENOMEM);
         }