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authorDavid Howells <dhowells@redhat.com>2013-12-02 12:24:18 +0100
committerDavid Howells <dhowells@redhat.com>2013-12-02 12:24:18 +0100
commit2480f57fb3023eb047c5f2d6dfefef41ab9b893c (patch)
tree65279528bb73307d236d8c614eb64dd6362e9e65
parentima: store address of template_fmt_copy in a pointer before calling strsep (diff)
downloadlinux-2480f57fb3023eb047c5f2d6dfefef41ab9b893c.tar.xz
linux-2480f57fb3023eb047c5f2d6dfefef41ab9b893c.zip
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:[<ffffffff811b4a51>] dput+0x21/0x2d0 ... Call Trace: [<ffffffff811a7b06>] path_put+0x16/0x30 [<ffffffff81235604>] big_key_destroy+0x44/0x60 [<ffffffff8122dc4b>] key_gc_unused_keys.constprop.2+0x5b/0xe0 [<ffffffff8122df2f>] key_garbage_collector+0x1df/0x3c0 [<ffffffff8107759b>] process_one_work+0x17b/0x460 [<ffffffff8107834b>] worker_thread+0x11b/0x400 [<ffffffff81078230>] ? rescuer_thread+0x3e0/0x3e0 [<ffffffff8107eb00>] kthread+0xc0/0xd0 [<ffffffff8107ea40>] ? kthread_create_on_node+0x110/0x110 [<ffffffff815c4bec>] ret_from_fork+0x7c/0xb0 [<ffffffff8107ea40>] ? kthread_create_on_node+0x110/0x110 Reported-by: Patrik Kis <pkis@redhat.com> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Stephen Gallagher <sgallagh@redhat.com>
-rw-r--r--security/keys/key.c8
1 files changed, 1 insertions, 7 deletions
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