From: DaeMyung Kang Date: Thu, 16 Apr 2026 21:17:35 +0000 (+0900) Subject: smb: server: fix max_connections off-by-one in tcp accept path X-Git-Tag: v7.1-rc1~34^2~14 X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=ce23158bfe584bd90d1918f279fdf9de57802012;p=thirdparty%2Flinux.git smb: server: fix max_connections off-by-one in tcp accept path The global max_connections check in ksmbd's TCP accept path counts the newly accepted connection with atomic_inc_return(), but then rejects the connection when the result is greater than or equal to server_conf.max_connections. That makes the effective limit one smaller than configured. For example: - max_connections=1 rejects the first connection - max_connections=2 allows only one connection The per-IP limit in the same function uses <= correctly because it counts only pre-existing connections. The global limit instead checks the post-increment total, so it should reject only when that total exceeds the configured maximum. Fix this by changing the comparison from >= to >, so exactly max_connections simultaneous connections are allowed and the next one is rejected. This matches the documented meaning of max_connections in fs/smb/server/ksmbd_netlink.h as the "Number of maximum simultaneous connections". Fixes: 0d0d4680db22 ("ksmbd: add max connections parameter") Cc: stable@vger.kernel.org Signed-off-by: DaeMyung Kang Acked-by: Namjae Jeon Signed-off-by: Steve French --- diff --git a/fs/smb/server/transport_tcp.c b/fs/smb/server/transport_tcp.c index 8d7fe71f525c..13b711ea575d 100644 --- a/fs/smb/server/transport_tcp.c +++ b/fs/smb/server/transport_tcp.c @@ -281,7 +281,7 @@ static int ksmbd_kthread_fn(void *p) skip_max_ip_conns_limit: if (server_conf.max_connections && - atomic_inc_return(&active_num_conn) >= server_conf.max_connections) { + atomic_inc_return(&active_num_conn) > server_conf.max_connections) { pr_info_ratelimited("Limit the maximum number of connections(%u)\n", atomic_read(&active_num_conn)); atomic_dec(&active_num_conn);