From: David Howells Date: Fri, 25 Sep 2015 15:30:08 +0000 (+0100) Subject: KEYS: Fix race between key destruction and finding a keyring by name X-Git-Tag: submit/tizen/20171013.014523~73 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=b0374db7a0a1445a56185a1e95f63096a4e29c19;p=profile%2Fmobile%2Fplatform%2Fkernel%2Flinux-3.10-sc7730.git KEYS: Fix race between key destruction and finding a keyring by name commit 94c4554ba07adbdde396748ee7ae01e86cf2d8d7 upstream. 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 Signed-off-by: David Howells Signed-off-by: Greg Kroah-Hartman [sw0312.kim: cherry-pick from linux-3.10.y to fix issue before applying CVE-2015-7872] Signed-off-by: Seung-Woo Kim Change-Id: I857d740596bf886d02fe149055df3191cad9e9db --- diff --git a/security/keys/gc.c b/security/keys/gc.c index 7978186..483ebdf 100644 --- a/security/keys/gc.c +++ b/security/keys/gc.c @@ -187,6 +187,10 @@ 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 */ @@ -201,10 +205,6 @@ 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);