rxrpc: Fix rxrpc_local leak in rxrpc_lookup_peer()

stable inclusion
from stable-v4.19.220
commit 913c24af2d13a3fd304462916ee98e298d56bdce
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9S23H
CVE: CVE-2021-47538
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=913c24af2d13a3fd304462916ee98e298d56bdce



--------------------------------

commit beacff50 upstream.

Need to call rxrpc_put_local() for peer candidate before kfree() as it
holds a ref to rxrpc_local.

[DH: v2: Changed to abstract the peer freeing code out into a function]

Fixes: 9ebeddef ("rxrpc: rxrpc_peer needs to hold a ref on the rxrpc_local record")
Signed-off-by: Eiichi Tsukata <eiichi.tsukata@nutanix.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/all/20211121041608.133740-2-eiichi.tsukata@nutanix.com/

 # v1
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Liu Chuang <liuchuang40@huawei.com>