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authorDavid Howells <dhowells@redhat.com>2015-09-25 16:30:08 +0100
committerDavid Howells <dhowells@redhat.com>2015-09-25 16:30:08 +0100
commit94c4554ba07adbdde396748ee7ae01e86cf2d8d7 (patch)
tree13cb745526d6c46d8d2f2c0dc30eba546f1f5857 /security
parentced255c0c5fb9ab52c9465982f23b1c14005ef8b (diff)
downloadlinux-linaro-stable-94c4554ba07adbdde396748ee7ae01e86cf2d8d7.tar.gz
KEYS: Fix race between key destruction and finding a keyring by name
There appears to be a race between: (1) key_gc_unused_keys() which frees key->security and then calls keyring_destroy() to unlink the name from the name list (2) find_keyring_by_name() which calls key_permission(), thus accessing key->security, on a key before checking to see whether the key usage is 0 (ie. the key is dead and might be cleaned up). Fix this by calling ->destroy() before cleaning up the core key data - including key->security. Reported-by: Petr Matousek <pmatouse@redhat.com> Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'security')
-rw-r--r--security/keys/gc.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/security/keys/gc.c b/security/keys/gc.c
index c7952375ac53..39eac1fd5706 100644
--- a/security/keys/gc.c
+++ b/security/keys/gc.c
@@ -134,6 +134,10 @@ static noinline void key_gc_unused_keys(struct list_head *keys)
kdebug("- %u", key->serial);
key_check(key);
+ /* Throw away the key data */
+ if (key->type->destroy)
+ key->type->destroy(key);
+
security_key_free(key);
/* deal with the user's key tracking and quota */
@@ -148,10 +152,6 @@ static noinline void key_gc_unused_keys(struct list_head *keys)
if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
atomic_dec(&key->user->nikeys);
- /* now throw away the key memory */
- if (key->type->destroy)
- key->type->destroy(key);
-
key_user_put(key->user);
kfree(key->description);