From: Xin Long <lucien.xin@xxxxxxxxx> commit 6f07e5f06c8712acc423485f657799fc8e11e56c upstream. Syzbot reported the following crash: BUG: KMSAN: uninit-value in memchr+0xce/0x110 lib/string.c:961 memchr+0xce/0x110 lib/string.c:961 string_is_valid net/tipc/netlink_compat.c:176 [inline] tipc_nl_compat_bearer_enable+0x2c4/0x910 net/tipc/netlink_compat.c:401 __tipc_nl_compat_doit net/tipc/netlink_compat.c:321 [inline] tipc_nl_compat_doit+0x3aa/0xaf0 net/tipc/netlink_compat.c:354 tipc_nl_compat_handle net/tipc/netlink_compat.c:1162 [inline] tipc_nl_compat_recv+0x1ae7/0x2750 net/tipc/netlink_compat.c:1265 genl_family_rcv_msg net/netlink/genetlink.c:601 [inline] genl_rcv_msg+0x185f/0x1a60 net/netlink/genetlink.c:626 netlink_rcv_skb+0x431/0x620 net/netlink/af_netlink.c:2477 genl_rcv+0x63/0x80 net/netlink/genetlink.c:637 netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline] netlink_unicast+0xf3e/0x1020 net/netlink/af_netlink.c:1336 netlink_sendmsg+0x127f/0x1300 net/netlink/af_netlink.c:1917 sock_sendmsg_nosec net/socket.c:622 [inline] sock_sendmsg net/socket.c:632 [inline] Uninit was created at: __alloc_skb+0x309/0xa20 net/core/skbuff.c:208 alloc_skb include/linux/skbuff.h:1012 [inline] netlink_alloc_large_skb net/netlink/af_netlink.c:1182 [inline] netlink_sendmsg+0xb82/0x1300 net/netlink/af_netlink.c:1892 sock_sendmsg_nosec net/socket.c:622 [inline] sock_sendmsg net/socket.c:632 [inline] It was triggered when the bearer name size < TIPC_MAX_BEARER_NAME, it would check with a wrong len/TLV_GET_DATA_LEN(msg->req), which also includes priority and disc_domain length. This patch is to fix it by checking it with a right length: 'TLV_GET_DATA_LEN(msg->req) - offsetof(struct tipc_bearer_config, name)'. Reported-by: syzbot+8b707430713eb46e1e45@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 @@ -388,7 +388,12 @@ static int tipc_nl_compat_bearer_enable( if (!bearer) return -EMSGSIZE; - len = min_t(int, TLV_GET_DATA_LEN(msg->req), TIPC_MAX_BEARER_NAME); + len = TLV_GET_DATA_LEN(msg->req); + len -= offsetof(struct tipc_bearer_config, name); + if (len <= 0) + return -EINVAL; + + len = min_t(int, len, TIPC_MAX_BEARER_NAME); if (!string_is_valid(b->name, len)) return -EINVAL;
