From: Cong Wang <xiyou.wangcong@gmail.com> stable inclusion from linux-4.19.143 commit 0d43753b0273731997a180f11d426d22f61bbb7d -------------------------------- [ Upstream commit 47733f9daf4fe4f7e0eb9e273f21ad3a19130487 ] __tipc_nl_compat_dumpit() has two callers, and it expects them to pass a valid nlmsghdr via arg->data. This header is artificial and crafted just for __tipc_nl_compat_dumpit(). tipc_nl_compat_publ_dump() does so by putting a genlmsghdr as well as some nested attribute, TIPC_NLA_SOCK. But the other caller tipc_nl_compat_dumpit() does not, this leaves arg->data uninitialized on this call path. Fix this by just adding a similar nlmsghdr without any payload in tipc_nl_compat_dumpit(). This bug exists since day 1, but the recent commit 6ea67769ff33 ("net: tipc: prepare attrs in __tipc_nl_compat_dumpit()") makes it easier to appear. Reported-and-tested-by: syzbot+0e7181deafa7e0b79923@syzkaller.appspotmail.com Fixes: d0796d1ef63d ("tipc: convert legacy nl bearer dump to nl compat") Cc: Jon Maloy <jmaloy@redhat.com> Cc: Ying Xue <ying.xue@windriver.com> Cc: Richard Alpe <richard.alpe@ericsson.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Acked-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Signed-off-by: Aichun Li <liaichun@huawei.com> Reviewed-by: wangxiaopeng <wangxiaopeng7@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- net/tipc/netlink_compat.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/net/tipc/netlink_compat.c b/net/tipc/netlink_compat.c index 29e684054abe..f8e111218a0e 100644 --- a/net/tipc/netlink_compat.c +++ b/net/tipc/netlink_compat.c @@ -255,8 +255,9 @@ static int __tipc_nl_compat_dumpit(struct tipc_nl_compat_cmd_dump *cmd, static int tipc_nl_compat_dumpit(struct tipc_nl_compat_cmd_dump *cmd, struct tipc_nl_compat_msg *msg) { - int err; + struct nlmsghdr *nlh; struct sk_buff *arg; + int err; if (msg->req_type && (!msg->req_size || !TLV_CHECK_TYPE(msg->req, msg->req_type))) @@ -285,6 +286,15 @@ static int tipc_nl_compat_dumpit(struct tipc_nl_compat_cmd_dump *cmd, return -ENOMEM; } + nlh = nlmsg_put(arg, 0, 0, tipc_genl_family.id, 0, NLM_F_MULTI); + if (!nlh) { + kfree_skb(arg); + kfree_skb(msg->rep); + msg->rep = NULL; + return -EMSGSIZE; + } + nlmsg_end(arg, nlh); + err = __tipc_nl_compat_dumpit(cmd, msg, arg); if (err) { kfree_skb(msg->rep); -- 2.25.1