From 2480f57fb3023eb047c5f2d6dfefef41ab9b893c Mon Sep 17 00:00:00 2001 From: David Howells Date: Mon, 2 Dec 2013 11:24:18 +0000 Subject: KEYS: Pre-clear struct key on allocation The second word of key->payload does not get initialised in key_alloc(), but the big_key type is relying on it having been cleared. The problem comes when big_key fails to instantiate a large key and doesn't then set the payload. The big_key_destroy() op is called from the garbage collector and this assumes that the dentry pointer stored in the second word will be NULL if instantiation did not complete. Therefore just pre-clear the entire struct key on allocation rather than trying to be clever and only initialising to 0 only those bits that aren't otherwise initialised. The lack of initialisation can lead to a bug report like the following if big_key failed to initialise its file: general protection fault: 0000 [#1] SMP Modules linked in: ... CPU: 0 PID: 51 Comm: kworker/0:1 Not tainted 3.10.0-53.el7.x86_64 #1 Hardware name: Dell Inc. PowerEdge 1955/0HC513, BIOS 1.4.4 12/09/2008 Workqueue: events key_garbage_collector task: ffff8801294f5680 ti: ffff8801296e2000 task.ti: ffff8801296e2000 RIP: 0010:[] dput+0x21/0x2d0 ... Call Trace: [] path_put+0x16/0x30 [] big_key_destroy+0x44/0x60 [] key_gc_unused_keys.constprop.2+0x5b/0xe0 [] key_garbage_collector+0x1df/0x3c0 [] process_one_work+0x17b/0x460 [] worker_thread+0x11b/0x400 [] ? rescuer_thread+0x3e0/0x3e0 [] kthread+0xc0/0xd0 [] ? kthread_create_on_node+0x110/0x110 [] ret_from_fork+0x7c/0xb0 [] ? kthread_create_on_node+0x110/0x110 Reported-by: Patrik Kis Signed-off-by: David Howells Reviewed-by: Stephen Gallagher --- security/keys/key.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) (limited to 'security') diff --git a/security/keys/key.c b/security/keys/key.c index 55d110f0aced..6e21c11e48bc 100644 --- a/security/keys/key.c +++ b/security/keys/key.c @@ -272,7 +272,7 @@ struct key *key_alloc(struct key_type *type, const char *desc, } /* allocate and initialise the key and its description */ - key = kmem_cache_alloc(key_jar, GFP_KERNEL); + key = kmem_cache_zalloc(key_jar, GFP_KERNEL); if (!key) goto no_memory_2; @@ -293,18 +293,12 @@ struct key *key_alloc(struct key_type *type, const char *desc, key->uid = uid; key->gid = gid; key->perm = perm; - key->flags = 0; - key->expiry = 0; - key->payload.data = NULL; - key->security = NULL; if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) key->flags |= 1 << KEY_FLAG_IN_QUOTA; if (flags & KEY_ALLOC_TRUSTED) key->flags |= 1 << KEY_FLAG_TRUSTED; - memset(&key->type_data, 0, sizeof(key->type_data)); - #ifdef KEY_DEBUGGING key->magic = KEY_DEBUG_MAGIC; #endif -- cgit v1.2.3