[PATCH 4.4 072/266] tipc: check link name with right length in tipc_nl_compat_link_set

From: Greg Kroah-Hartman
Date: Wed May 15 2019 - 08:13:13 EST


From: Xin Long <lucien.xin@xxxxxxxxx>

commit 8c63bf9ab4be8b83bd8c34aacfd2f1d2c8901c8a upstream.

A similar issue as fixed by Patch "tipc: check bearer name with right
length in tipc_nl_compat_bearer_enable" was also found by syzbot in
tipc_nl_compat_link_set().

The length to check with should be 'TLV_GET_DATA_LEN(msg->req) -
offsetof(struct tipc_link_config, name)'.

Reported-by: syzbot+de00a87b8644a582ae79@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
net/tipc/netlink_compat.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

--- a/net/tipc/netlink_compat.c
+++ b/net/tipc/netlink_compat.c
@@ -738,7 +738,12 @@ static int tipc_nl_compat_link_set(struc

lc = (struct tipc_link_config *)TLV_DATA(msg->req);

- len = min_t(int, TLV_GET_DATA_LEN(msg->req), TIPC_MAX_LINK_NAME);
+ len = TLV_GET_DATA_LEN(msg->req);
+ len -= offsetof(struct tipc_link_config, name);
+ if (len <= 0)
+ return -EINVAL;
+
+ len = min_t(int, len, TIPC_MAX_LINK_NAME);
if (!string_is_valid(lc->name, len))
return -EINVAL;