From a8b9b96e959f3c035af20b1bd2ba67b0b7269b19 Mon Sep 17 00:00:00 2001 From: Ying Xue Date: Mon, 21 Apr 2014 10:55:52 +0800 Subject: [PATCH] tipc: fix race in disc create/delete Commit a21a584d6720ce349b05795b9bcfab3de8e58419 (tipc: fix neighbor detection problem after hw address change) introduces a race condition involving tipc_disc_delete() and tipc_disc_add/remove_dest that can cause TIPC to dereference the pointer to the bearer discovery request structure after it has been freed since a stray pointer is left in the bearer structure. In order to fix the issue, the process of resetting the discovery request handler is optimized: the discovery request handler and request buffer are just reset instead of being freed, allocated and initialized. As the request point is always valid and the request's lock is taken while the request handler is reset, the race doesn't happen any more. Reported-by: Erik Hugne Signed-off-by: Ying Xue Reviewed-by: Erik Hugne Tested-by: Erik Hugne Signed-off-by: David S. Miller --- net/tipc/bearer.c | 3 +-- net/tipc/discover.c | 53 ++++++++++++++++++++++++++++++--------------- net/tipc/discover.h | 1 + 3 files changed, 37 insertions(+), 20 deletions(-) diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c index 3abd9702b887..f3259d4133b6 100644 --- a/net/tipc/bearer.c +++ b/net/tipc/bearer.c @@ -365,9 +365,8 @@ restart: static int tipc_reset_bearer(struct tipc_bearer *b_ptr) { pr_info("Resetting bearer <%s>\n", b_ptr->name); - tipc_disc_delete(b_ptr->link_req); tipc_link_reset_list(b_ptr->identity); - tipc_disc_create(b_ptr, &b_ptr->bcast_addr); + tipc_disc_reset(b_ptr); return 0; } diff --git a/net/tipc/discover.c b/net/tipc/discover.c index 3a8f211f08c7..ada42e436f5e 100644 --- a/net/tipc/discover.c +++ b/net/tipc/discover.c @@ -71,22 +71,19 @@ struct tipc_link_req { * @type: message type (request or response) * @b_ptr: ptr to bearer issuing message */ -static struct sk_buff *tipc_disc_init_msg(u32 type, struct tipc_bearer *b_ptr) +static void tipc_disc_init_msg(struct sk_buff *buf, u32 type, + struct tipc_bearer *b_ptr) { - struct sk_buff *buf = tipc_buf_acquire(INT_H_SIZE); struct tipc_msg *msg; u32 dest_domain = b_ptr->domain; - if (buf) { - msg = buf_msg(buf); - tipc_msg_init(msg, LINK_CONFIG, type, INT_H_SIZE, dest_domain); - msg_set_non_seq(msg, 1); - msg_set_node_sig(msg, tipc_random); - msg_set_dest_domain(msg, dest_domain); - msg_set_bc_netid(msg, tipc_net_id); - b_ptr->media->addr2msg(&b_ptr->addr, msg_media_addr(msg)); - } - return buf; + msg = buf_msg(buf); + tipc_msg_init(msg, LINK_CONFIG, type, INT_H_SIZE, dest_domain); + msg_set_non_seq(msg, 1); + msg_set_node_sig(msg, tipc_random); + msg_set_dest_domain(msg, dest_domain); + msg_set_bc_netid(msg, tipc_net_id); + b_ptr->media->addr2msg(&b_ptr->addr, msg_media_addr(msg)); } /** @@ -241,8 +238,9 @@ void tipc_disc_rcv(struct sk_buff *buf, struct tipc_bearer *b_ptr) link_fully_up = link_working_working(link); if ((type == DSC_REQ_MSG) && !link_fully_up) { - rbuf = tipc_disc_init_msg(DSC_RESP_MSG, b_ptr); + rbuf = tipc_buf_acquire(INT_H_SIZE); if (rbuf) { + tipc_disc_init_msg(rbuf, DSC_RESP_MSG, b_ptr); tipc_bearer_send(b_ptr->identity, rbuf, &media_addr); kfree_skb(rbuf); } @@ -349,12 +347,11 @@ int tipc_disc_create(struct tipc_bearer *b_ptr, struct tipc_media_addr *dest) if (!req) return -ENOMEM; - req->buf = tipc_disc_init_msg(DSC_REQ_MSG, b_ptr); - if (!req->buf) { - kfree(req); - return -ENOMSG; - } + req->buf = tipc_buf_acquire(INT_H_SIZE); + if (!req->buf) + return -ENOMEM; + tipc_disc_init_msg(req->buf, DSC_REQ_MSG, b_ptr); memcpy(&req->dest, dest, sizeof(*dest)); req->bearer_id = b_ptr->identity; req->domain = b_ptr->domain; @@ -379,3 +376,23 @@ void tipc_disc_delete(struct tipc_link_req *req) kfree_skb(req->buf); kfree(req); } + +/** + * tipc_disc_reset - reset object to send periodic link setup requests + * @b_ptr: ptr to bearer issuing requests + * @dest_domain: network domain to which links can be established + */ +void tipc_disc_reset(struct tipc_bearer *b_ptr) +{ + struct tipc_link_req *req = b_ptr->link_req; + + spin_lock_bh(&req->lock); + tipc_disc_init_msg(req->buf, DSC_REQ_MSG, b_ptr); + req->bearer_id = b_ptr->identity; + req->domain = b_ptr->domain; + req->num_nodes = 0; + req->timer_intv = TIPC_LINK_REQ_INIT; + k_start_timer(&req->timer, req->timer_intv); + tipc_bearer_send(req->bearer_id, req->buf, &req->dest); + spin_unlock_bh(&req->lock); +} diff --git a/net/tipc/discover.h b/net/tipc/discover.h index 07f34729459d..515b57392f4d 100644 --- a/net/tipc/discover.h +++ b/net/tipc/discover.h @@ -41,6 +41,7 @@ struct tipc_link_req; int tipc_disc_create(struct tipc_bearer *b_ptr, struct tipc_media_addr *dest); void tipc_disc_delete(struct tipc_link_req *req); +void tipc_disc_reset(struct tipc_bearer *b_ptr); void tipc_disc_add_dest(struct tipc_link_req *req); void tipc_disc_remove_dest(struct tipc_link_req *req); void tipc_disc_rcv(struct sk_buff *buf, struct tipc_bearer *b_ptr); -- 2.20.1