From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44880) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eZPLg-0001bK-Jc for qemu-devel@nongnu.org; Wed, 10 Jan 2018 17:59:57 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eZPLf-0004jJ-OQ for qemu-devel@nongnu.org; Wed, 10 Jan 2018 17:59:56 -0500 From: Eric Blake Date: Wed, 10 Jan 2018 16:59:43 -0600 Message-Id: <20180110225944.17920-2-eblake@redhat.com> In-Reply-To: <20180110225944.17920-1-eblake@redhat.com> References: <20180110225944.17920-1-eblake@redhat.com> Subject: [Qemu-devel] [PULL 1/2] nbd/server: add additional assert to nbd_export_put List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Vladimir Sementsov-Ogievskiy , Paolo Bonzini , "open list:Network Block Dev..." From: Vladimir Sementsov-Ogievskiy This place is not obvious, nbd_export_close may theoretically reduce refcount to 0. It may happen if someone calls nbd_export_put on named export not through nbd_export_set_name when refcount is 1. Signed-off-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Eric Blake Reviewed-by: Max Reitz Message-Id: <20171207155102.66622-2-vsementsov@virtuozzo.com> Signed-off-by: Eric Blake --- nbd/server.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/nbd/server.c b/nbd/server.c index e443b3cf5c..6cf2eeb2c1 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -1190,6 +1190,12 @@ void nbd_export_put(NBDExport *exp) nbd_export_close(exp); } + /* nbd_export_close() may theoretically reduce refcount to 0. It may happen + * if someone calls nbd_export_put() on named export not through + * nbd_export_set_name() when refcount is 1. So, let's assert that + * it is > 0. + */ + assert(exp->refcount > 0); if (--exp->refcount == 0) { assert(exp->name == NULL); assert(exp->description == NULL); -- 2.14.3