From 7e27e8d6130c5e88fac9ddec4249f7f2337fe7f8 Mon Sep 17 00:00:00 2001 From: Junwei Hu Date: Thu, 16 May 2019 10:51:15 +0800 Subject: [PATCH] tipc: switch order of device registration to fix a crash When tipc is loaded while many processes try to create a TIPC socket, a crash occurs: PANIC: Unable to handle kernel paging request at virtual address "dfff20000000021d" pc : tipc_sk_create+0x374/0x1180 [tipc] lr : tipc_sk_create+0x374/0x1180 [tipc] Exception class = DABT (current EL), IL = 32 bits Call trace: tipc_sk_create+0x374/0x1180 [tipc] __sock_create+0x1cc/0x408 __sys_socket+0xec/0x1f0 __arm64_sys_socket+0x74/0xa8 ... This is due to race between sock_create and unfinished register_pernet_device. tipc_sk_insert tries to do "net_generic(net, tipc_net_id)". but tipc_net_id is not initialized yet. So switch the order of the two to close the race. This can be reproduced with multiple processes doing socket(AF_TIPC, ...) and one process doing module removal. Fixes: a62fbccecd62 ("tipc: make subscriber server support net namespace") Signed-off-by: Junwei Hu Reported-by: Wang Wang Reviewed-by: Xiaogang Wang Signed-off-by: David S. Miller --- net/tipc/core.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/net/tipc/core.c b/net/tipc/core.c index 27cccd101ef6..ddd2e0f67c07 100644 --- a/net/tipc/core.c +++ b/net/tipc/core.c @@ -131,10 +131,6 @@ static int __init tipc_init(void) if (err) goto out_netlink_compat; - err = tipc_socket_init(); - if (err) - goto out_socket; - err = tipc_register_sysctl(); if (err) goto out_sysctl; @@ -143,6 +139,10 @@ static int __init tipc_init(void) if (err) goto out_pernet; + err = tipc_socket_init(); + if (err) + goto out_socket; + err = tipc_bearer_setup(); if (err) goto out_bearer; @@ -150,12 +150,12 @@ static int __init tipc_init(void) pr_info("Started in single node mode\n"); return 0; out_bearer: + tipc_socket_stop(); +out_socket: unregister_pernet_subsys(&tipc_net_ops); out_pernet: tipc_unregister_sysctl(); out_sysctl: - tipc_socket_stop(); -out_socket: tipc_netlink_compat_stop(); out_netlink_compat: tipc_netlink_stop(); @@ -167,10 +167,10 @@ out_netlink: static void __exit tipc_exit(void) { tipc_bearer_cleanup(); + tipc_socket_stop(); unregister_pernet_subsys(&tipc_net_ops); tipc_netlink_stop(); tipc_netlink_compat_stop(); - tipc_socket_stop(); tipc_unregister_sysctl(); pr_info("Deactivated\n"); -- 2.30.2