[PATCH 6.12 123/460] tipc: fix divide-by-zero in tipc_sk_filter_connect()

Greg Kroah-Hartman
2026-03-23T14:18:17Z

6.12-stable review patch. If anyone has any objections, please let me know.

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

From: Mehul Rao <mehulrao@gmail.com>

commit 6c5a9baa15de240e747263aba435a0951da8d8d2 upstream.

A user can set conn_timeout to any value via
setsockopt(TIPC_CONN_TIMEOUT), including values less than 4. When a
SYN is rejected with TIPC_ERR_OVERLOAD and the retry path in
tipc_sk_filter_connect() executes:

delay %= (tsk->conn_timeout / 4);

If conn_timeout is in the range [0, 3], the integer division yields 0,
and the modulo operation triggers a divide-by-zero exception, causing a
kernel oops/panic.

Fix this by clamping conn_timeout to a minimum of 4 at the point of use
in tipc_sk_filter_connect().

Oops: divide error: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 119 Comm: poc-F144 Not tainted 7.0.0-rc2+
RIP: 0010:tipc_sk_filter_rcv (net/tipc/socket.c:2236 net/tipc/socket.c:2362)
Call Trace:
tipc_sk_backlog_rcv (include/linux/instrumented.h:82 include/linux/atomic/atomic-instrumented.h:32 include/net/sock.h:2357 net/tipc/socket.c:2406)
__release_sock (include/net/sock.h:1185 net/core/sock.c:3213)
release_sock (net/core/sock.c:3797)
tipc_connect (net/tipc/socket.c:2570)
__sys_connect (include/linux/file.h:62 include/linux/file.h:83 net/socket.c:2098)

Fixes: 6787927475e5 ("tipc: buffer overflow handling in listener socket")
Cc: stable@vger.kernel.org
Signed-off-by: Mehul Rao <mehulrao@gmail.com>
Reviewed-by: Tung Nguyen <tung.quang.nguyen@est.tech>
Link: https://patch.msgid.link/20260310170730.28841-1-mehulrao@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/tipc/socket.c | 2 ++
1 file changed, 2 insertions(+)

--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -2233,6 +2233,8 @@ static bool tipc_sk_filter_connect(struc
if (skb_queue_empty(&sk->sk_write_queue))
break;
get_random_bytes(&delay, 2);
+ if (tsk->conn_timeout < 4)
+ tsk->conn_timeout = 4;
delay %= (tsk->conn_timeout / 4);
delay = msecs_to_jiffies(delay + 100);
sk_reset_timer(sk, &sk->sk_timer, jiffies + delay);