Re: [PATCH RESEND] mac802154: Fix uninit-value access in ieee802154_hdr_push_sechdr

[Alexander Aring]

Hi,

On Thu, Dec 14, 2023 at 10:01 PM Alexander Aring <aahringo@xxxxxxxxxx> wrote:
>
> Hi,
>
> On Mon, Dec 4, 2023 at 3:57 AM Miquel Raynal <miquel.raynal@xxxxxxxxxxx> wrote:
> >
> > Hi Zhang,
> >
> > zhang_shurong@xxxxxxxxxxx wrote on Sat,  2 Dec 2023 22:58:52 +0800:
> >
> > > The syzkaller reported an issue:
> >
> > Subject should start with [PATCH wpan]
> >
> > >
> > > BUG: KMSAN: uninit-value in ieee802154_hdr_push_sechdr net/ieee802154/header_ops.c:54 [inline]
> > > BUG: KMSAN: uninit-value in ieee802154_hdr_push+0x971/0xb90 net/ieee802154/header_ops.c:108
> > >  ieee802154_hdr_push_sechdr net/ieee802154/header_ops.c:54 [inline]
> > >  ieee802154_hdr_push+0x971/0xb90 net/ieee802154/header_ops.c:108
> > >  ieee802154_header_create+0x9c0/0xc00 net/mac802154/iface.c:396
> > >  wpan_dev_hard_header include/net/cfg802154.h:494 [inline]
> > >  dgram_sendmsg+0xd1d/0x1500 net/ieee802154/socket.c:677
> > >  ieee802154_sock_sendmsg+0x91/0xc0 net/ieee802154/socket.c:96
> > >  sock_sendmsg_nosec net/socket.c:725 [inline]
> > >  sock_sendmsg net/socket.c:748 [inline]
> > >  ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2494
> > >  ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2548
> > >  __sys_sendmsg+0x225/0x3c0 net/socket.c:2577
> > >  __compat_sys_sendmsg net/compat.c:346 [inline]
> > >  __do_compat_sys_sendmsg net/compat.c:353 [inline]
> > >  __se_compat_sys_sendmsg net/compat.c:350 [inline]
> > >
> > > We found hdr->key_id_mode is uninitialized in mac802154_set_header_security()
> > > which indicates hdr.fc.security_enabled should be 0. However, it is set to be cb->secen before.
> > > Later, ieee802154_hdr_push_sechdr is invoked, causing KMSAN complains uninit-value issue.
> >
> > I am not too deeply involved in the security header but for me it feels
> > like your patch does the opposite of what's needed. We should maybe
> > initialize hdr->key_id_mode based on the value in cb->secen, no? (maybe
> > Alexander will have a better understanding than I have).
>
> I can't help yet with a better answer why syzkaller reports it but it
> will break things as we using skb->cb to pass additional parameters
> through header_ops->create()... in this case it is some sockopts of
> af802154, I guess.
>

Maybe we just need to init some "more" defaults in [0]

- Alex

[0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/net/ieee802154/socket.c?h=v6.7-rc5#n474