There is uninit value bug in dgram_sendmsg function in
net/ieee802154/socket.c when the length of valid data pointed by the
msg->msg_name isn't verified.

This length is specified by msg->msg_namelen. Function
ieee802154_addr_from_sa is called by dgram_sendmsg, which use
msg->msg_name as struct sockaddr_ieee802154* and read it, that will
eventually lead to uninit value read. So we should check the length of
msg->msg_name is not less than sizeof(struct sockaddr_ieee802154)
before entering the ieee802154_addr_from_sa.

Signed-off-by: Haimin Zhang <tcs_kernel@tencent.com>
---
 net/ieee802154/socket.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/ieee802154/socket.c b/net/ieee802154/socket.c
index 718fb77bb..efbe08590 100644
--- a/net/ieee802154/socket.c
+++ b/net/ieee802154/socket.c
@@ -655,6 +655,10 @@ static int dgram_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 	if (msg->msg_name) {
 		DECLARE_SOCKADDR(struct sockaddr_ieee802154*,
 				 daddr, msg->msg_name);
+		if (msg->msg_namelen < sizeof(*daddr)) {
+			err = -EINVAL;
+			goto out_skb;
+		}
 
 		ieee802154_addr_from_sa(&dst_addr, &daddr->addr);
 	} else {
-- 
2.27.0

Hello.

On 22.08.22 09:19, Haimin Zhang wrote:
> There is uninit value bug in dgram_sendmsg function in
> net/ieee802154/socket.c when the length of valid data pointed by the
> msg->msg_name isn't verified.
> 
> This length is specified by msg->msg_namelen. Function
> ieee802154_addr_from_sa is called by dgram_sendmsg, which use
> msg->msg_name as struct sockaddr_ieee802154* and read it, that will
> eventually lead to uninit value read. So we should check the length of
> msg->msg_name is not less than sizeof(struct sockaddr_ieee802154)
> before entering the ieee802154_addr_from_sa.
> 
> Signed-off-by: Haimin Zhang <tcs_kernel@tencent.com>


This patch has been applied to the wpan tree and will be
part of the next pull request to net. Thanks!

Btw, I got a warning from the checkpatch script that your author and SOB 
email addresses do not match. Might be a good idea to fix this.
If you are having trouble to send patches through the company mail 
server there is always the option to use the gmail address for sending 
the mail and an internal From: header in the patch to fix up the author.

regards
Stefan Schmidt

Hi,

On Tue, Aug 23, 2022 at 5:42 AM Stefan Schmidt
<stefan@datenfreihafen.org> wrote:
>
> Hello.
>
> On 22.08.22 09:19, Haimin Zhang wrote:
> > There is uninit value bug in dgram_sendmsg function in
> > net/ieee802154/socket.c when the length of valid data pointed by the
> > msg->msg_name isn't verified.
> >
> > This length is specified by msg->msg_namelen. Function
> > ieee802154_addr_from_sa is called by dgram_sendmsg, which use
> > msg->msg_name as struct sockaddr_ieee802154* and read it, that will
> > eventually lead to uninit value read. So we should check the length of
> > msg->msg_name is not less than sizeof(struct sockaddr_ieee802154)
> > before entering the ieee802154_addr_from_sa.
> >
> > Signed-off-by: Haimin Zhang <tcs_kernel@tencent.com>
>
>
> This patch has been applied to the wpan tree and will be
> part of the next pull request to net. Thanks!

For me this patch is buggy or at least it is questionable how to deal
with the size of ieee802154_addr_sa here.

There should be a helper to calculate the size which depends on the
addr_type field. It is not required to send the last 6 bytes if
addr_type is IEEE802154_ADDR_SHORT.
Nitpick is that we should check in the beginning of that function.

- Alex

Hello Alex.

On 23.08.22 14:22, Alexander Aring wrote:
> Hi,
> 
> On Tue, Aug 23, 2022 at 5:42 AM Stefan Schmidt
> <stefan@datenfreihafen.org> wrote:
>>
>> Hello.
>>
>> On 22.08.22 09:19, Haimin Zhang wrote:
>>> There is uninit value bug in dgram_sendmsg function in
>>> net/ieee802154/socket.c when the length of valid data pointed by the
>>> msg->msg_name isn't verified.
>>>
>>> This length is specified by msg->msg_namelen. Function
>>> ieee802154_addr_from_sa is called by dgram_sendmsg, which use
>>> msg->msg_name as struct sockaddr_ieee802154* and read it, that will
>>> eventually lead to uninit value read. So we should check the length of
>>> msg->msg_name is not less than sizeof(struct sockaddr_ieee802154)
>>> before entering the ieee802154_addr_from_sa.
>>>
>>> Signed-off-by: Haimin Zhang <tcs_kernel@tencent.com>
>>
>>
>> This patch has been applied to the wpan tree and will be
>> part of the next pull request to net. Thanks!
> 
> For me this patch is buggy or at least it is questionable how to deal
> with the size of ieee802154_addr_sa here.

You are right. I completely missed this. Thanks for spotting!

> There should be a helper to calculate the size which depends on the
> addr_type field. It is not required to send the last 6 bytes if
> addr_type is IEEE802154_ADDR_SHORT.
> Nitpick is that we should check in the beginning of that function.

Haimin, in ieee802154 we could have two different sizes for 
ieee802154_addr_sa depending on the addr_type. We have short and 
extended addresses.

Could you please rework this patch to take this into account as Alex 
suggested?

I reverted your original patch from my tree.

regards
Stefan Schmidt

Thanks to all.
I have sent patch v2 to fix this.

On Mon, Aug 29, 2022 at 5:08 PM Stefan Schmidt
<stefan@datenfreihafen.org> wrote:
>
>
> Hello Alex.
>
> On 23.08.22 14:22, Alexander Aring wrote:
> > Hi,
> >
> > On Tue, Aug 23, 2022 at 5:42 AM Stefan Schmidt
> > <stefan@datenfreihafen.org> wrote:
> >>
> >> Hello.
> >>
> >> On 22.08.22 09:19, Haimin Zhang wrote:
> >>> There is uninit value bug in dgram_sendmsg function in
> >>> net/ieee802154/socket.c when the length of valid data pointed by the
> >>> msg->msg_name isn't verified.
> >>>
> >>> This length is specified by msg->msg_namelen. Function
> >>> ieee802154_addr_from_sa is called by dgram_sendmsg, which use
> >>> msg->msg_name as struct sockaddr_ieee802154* and read it, that will
> >>> eventually lead to uninit value read. So we should check the length of
> >>> msg->msg_name is not less than sizeof(struct sockaddr_ieee802154)
> >>> before entering the ieee802154_addr_from_sa.
> >>>
> >>> Signed-off-by: Haimin Zhang <tcs_kernel@tencent.com>
> >>
> >>
> >> This patch has been applied to the wpan tree and will be
> >> part of the next pull request to net. Thanks!
> >
> > For me this patch is buggy or at least it is questionable how to deal
> > with the size of ieee802154_addr_sa here.
>
> You are right. I completely missed this. Thanks for spotting!
>
> > There should be a helper to calculate the size which depends on the
> > addr_type field. It is not required to send the last 6 bytes if
> > addr_type is IEEE802154_ADDR_SHORT.
> > Nitpick is that we should check in the beginning of that function.
>
> Haimin, in ieee802154 we could have two different sizes for
> ieee802154_addr_sa depending on the addr_type. We have short and
> extended addresses.
>
> Could you please rework this patch to take this into account as Alex
> suggested?
>
> I reverted your original patch from my tree.
>
> regards
> Stefan Schmidt