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Subject[PATCH 3.16 143/346] sysv, ipc: fix security-layer leaking
3.16.39-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Fabian Frederick <fabf@skynet.be>

commit 9b24fef9f0410fb5364245d6cc2bd044cc064007 upstream.

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
ipc/msg.c | 2 +-
ipc/sem.c | 12 ++++++------
2 files changed, 7 insertions(+), 7 deletions(-)

--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -678,7 +678,7 @@ long do_msgsnd(int msqid, long mtype, vo
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;
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -442,7 +442,7 @@ static inline struct sem_array *sem_obta
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)
@@ -1385,7 +1385,7 @@ static int semctl_main(struct ipc_namesp
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;
}

@@ -1419,20 +1419,20 @@ static int semctl_main(struct ipc_namesp
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;
}
@@ -1722,7 +1722,7 @@ static struct sem_undo *find_alloc_undo(
/* 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);
}

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