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Patch "sysv, ipc: fix security-layer leaking" has been added to the 4.4-stable tree

PATCH [email protected] 1 participant 1 message Aug 14, 2016 Stable branch

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This is a note to let you know that I've just added the patch titled

sysv, ipc: fix security-layer leaking

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
sysv-ipc-fix-security-layer-leaking.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 9b24fef9f0410fb5364245d6cc2bd044cc064007 Mon Sep 17 00:00:00 2001

From: Fabian Frederick <[email protected]>
Date: Tue, 2 Aug 2016 14:03:07 -0700
Subject: sysv, ipc: fix security-layer leaking

From: Fabian Frederick <[email protected]>

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/[email protected] open here
Signed-off-by Fabian Frederick <[email protected]>
Cc Davidlohr Bueso <[email protected]>
Cc Manfred Spraul <[email protected]>
Signed-off-by Andrew Morton <[email protected]>
Signed-off-by Linus Torvalds <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 ipc/msg.c |    2 +-
 ipc/sem.c |   12 ++++++------
 2 files changed, 7 insertions(+), 7 deletions(-)
ipc/msg.c +1 -1
@@ -680,7 +680,7 @@ 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;
ipc/sem.c +6 -6
@@ -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);
 	}

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/sysv-ipc-fix-security-layer-leaking.patch