diff mbox series

[net,1/2] tipc: set con sock in tipc_conn_alloc

Message ID bc7bd3183f1c275c820690fc65b708238fe9e38e.1668807842.git.lucien.xin@gmail.com (mailing list archive)
State Accepted
Commit 0e5d56c64afcd6fd2d132ea972605b66f8a7d3c4
Delegated to: Netdev Maintainers
Headers show
Series tipc: fix two race issues in tipc_conn_alloc | expand

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Context Check Description
netdev/tree_selection success Clearly marked for net
netdev/fixes_present success Fixes tag present in non-next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers fail 1 blamed authors not CCed: paul.gortmaker@windriver.com; 1 maintainers not CCed: paul.gortmaker@windriver.com
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch warning WARNING: line length of 84 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Xin Long Nov. 18, 2022, 9:45 p.m. UTC
A crash was reported by Wei Chen:

  BUG: kernel NULL pointer dereference, address: 0000000000000018
  RIP: 0010:tipc_conn_close+0x12/0x100
  Call Trace:
   tipc_topsrv_exit_net+0x139/0x320
   ops_exit_list.isra.9+0x49/0x80
   cleanup_net+0x31a/0x540
   process_one_work+0x3fa/0x9f0
   worker_thread+0x42/0x5c0

It was caused by !con->sock in tipc_conn_close(). In tipc_topsrv_accept(),
con is allocated in conn_idr then its sock is set:

  con = tipc_conn_alloc();
  ...                    <----[1]
  con->sock = newsock;

If tipc_conn_close() is called in anytime of [1], the null-pointer-def
is triggered by con->sock->sk due to con->sock is not yet set.

This patch fixes it by moving the con->sock setting to tipc_conn_alloc()
under s->idr_lock. So that con->sock can never be NULL when getting the
con from s->conn_idr. It will be also safer to move con->server and flag
CF_CONNECTED setting under s->idr_lock, as they should all be set before
tipc_conn_alloc() is called.

Fixes: c5fa7b3cf3cb ("tipc: introduce new TIPC server infrastructure")
Reported-by: Wei Chen <harperchen1110@gmail.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 net/tipc/topsrv.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/net/tipc/topsrv.c b/net/tipc/topsrv.c
index d92ec92f0b71..b0f9aa521670 100644
--- a/net/tipc/topsrv.c
+++ b/net/tipc/topsrv.c
@@ -176,7 +176,7 @@  static void tipc_conn_close(struct tipc_conn *con)
 	conn_put(con);
 }
 
-static struct tipc_conn *tipc_conn_alloc(struct tipc_topsrv *s)
+static struct tipc_conn *tipc_conn_alloc(struct tipc_topsrv *s, struct socket *sock)
 {
 	struct tipc_conn *con;
 	int ret;
@@ -202,10 +202,11 @@  static struct tipc_conn *tipc_conn_alloc(struct tipc_topsrv *s)
 	}
 	con->conid = ret;
 	s->idr_in_use++;
-	spin_unlock_bh(&s->idr_lock);
 
 	set_bit(CF_CONNECTED, &con->flags);
 	con->server = s;
+	con->sock = sock;
+	spin_unlock_bh(&s->idr_lock);
 
 	return con;
 }
@@ -467,7 +468,7 @@  static void tipc_topsrv_accept(struct work_struct *work)
 		ret = kernel_accept(lsock, &newsock, O_NONBLOCK);
 		if (ret < 0)
 			return;
-		con = tipc_conn_alloc(srv);
+		con = tipc_conn_alloc(srv, newsock);
 		if (IS_ERR(con)) {
 			ret = PTR_ERR(con);
 			sock_release(newsock);
@@ -479,7 +480,6 @@  static void tipc_topsrv_accept(struct work_struct *work)
 		newsk->sk_data_ready = tipc_conn_data_ready;
 		newsk->sk_write_space = tipc_conn_write_space;
 		newsk->sk_user_data = con;
-		con->sock = newsock;
 		write_unlock_bh(&newsk->sk_callback_lock);
 
 		/* Wake up receive process in case of 'SYN+' message */
@@ -577,12 +577,11 @@  bool tipc_topsrv_kern_subscr(struct net *net, u32 port, u32 type, u32 lower,
 	sub.filter = filter;
 	*(u64 *)&sub.usr_handle = (u64)port;
 
-	con = tipc_conn_alloc(tipc_topsrv(net));
+	con = tipc_conn_alloc(tipc_topsrv(net), NULL);
 	if (IS_ERR(con))
 		return false;
 
 	*conid = con->conid;
-	con->sock = NULL;
 	rc = tipc_conn_rcv_sub(tipc_topsrv(net), con, &sub);
 	if (rc >= 0)
 		return true;