>> > > >> > > 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. [1] https://syzkaller.appspot.com/bug?extid=60a66d44892b66b56545 Hoping not to have spewed too much nonsense here... With regards, Nikita
