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tipc: fix uninit skb->data in tipc_nl_compat_dumpit()

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__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>
This commit is contained in:
Cong Wang 2020-08-15 16:29:15 -07:00 committed by David S. Miller
parent 8c26544f5a
commit 47733f9daf
1 changed files with 11 additions and 1 deletions
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12
net/tipc/netlink_compat.c
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@ -275,8 +275,9 @@ err_out:
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) struct tipc_nl_compat_msg *msg)
{ {
int err; struct nlmsghdr *nlh;
struct sk_buff *arg; struct sk_buff *arg;
int err;
if (msg->req_type && (!msg->req_size || if (msg->req_type && (!msg->req_size ||
!TLV_CHECK_TYPE(msg->req, msg->req_type))) !TLV_CHECK_TYPE(msg->req, msg->req_type)))
@ -305,6 +306,15 @@ static int tipc_nl_compat_dumpit(struct tipc_nl_compat_cmd_dump *cmd,
return -ENOMEM; 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); err = __tipc_nl_compat_dumpit(cmd, msg, arg);
if (err) { if (err) {
kfree_skb(msg->rep); kfree_skb(msg->rep);