Hi, On Sun, Jan 14, 2024 at 10:32 PM Alexander Aring <aahringo@xxxxxxxxxx> wrote: > > Hi, > > On Fri, Jan 12, 2024 at 8:16 AM Nikita Zhandarovich > <n.zhandarovich@xxxxxxxxxx> wrote: > > > > >> > > > > >> > > 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/ieee8= > > > 02154/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_se= > > > curity() > > >> > > which indicates hdr.fc.security_enabled should be 0. However, it is s= > > > et 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=3Dv6.7-rc5#n474 > > > > Hello, > > > > I was looking into the same issue (now present in syzbot [1]) and since it has a > > C-repro, the error is easy to recreate. Apparently, despite cb->secen (and > > hdr.fc.security_enabled accordingly) being equal 1, mac802154_set_header_security() > > finishes with 0 in: > > > > if (!params.enabled || > > (cb->secen_override && !cb->secen) || > > !params.out_level) > > return 0; > > > > Not presuming to understand the issue fully but if we do end up leaving > > mac802154_set_header_security() early, should we init hdr->key_id_mode > > with IEEE802154_SCF_KEY_IMPLICIT before returning with 0? > > I imagine that reseting hdr.fc.security_enabled to 0 ourselves in this > > case is a wrong way to go too. > > > > I think here are two problems: > > 1. > When (in any way) secen path is hit then we should make sure some > other security parameters are set, if not return with an error. This > needs to be done somewhere in the 802.15.4 socket code. [0] > This would require that we init them with some invalid value defaults but I think because we are using bit fields, we need to change the whole struct to make some invalid number range available. I am happy to init those values to some value at [0] to at least get rid of the uninit value warning. We can change it so that it fails at send() afterwards, I think it should fail in some later path of the implementation that ends in a kernel log message. - Alex [0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/net/ieee802154/socket.c#n474
