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). > Since mac802154_set_header_security() sets hdr.fc.security_enabled based on the variables > ieee802154_sub_if_data *sdata and ieee802154_mac_cb *cb in a collaborative manner. > Therefore, we should not set security_enabled prior to mac802154_set_header_security(). > > Fixed it by removing the line that sets the hdr.fc.security_enabled. > > Syzkaller don't provide repro, and I provide a syz repro like: > r0 = syz_init_net_socket$802154_dgram(0x24, 0x2, 0x0) > setsockopt$WPAN_SECURITY(r0, 0x0, 0x1, &(0x7f0000000000)=0x2, 0x4) > setsockopt$WPAN_SECURITY(r0, 0x0, 0x1, &(0x7f0000000080), 0x4) > sendmsg$802154_dgram(r0, &(0x7f0000000100)={&(0x7f0000000040)={0x24, @short}, 0x14, &(0x7f00000000c0)={0x0}}, 0x0) > > Fixes: 32edc40ae65c ("ieee802154: change _cb handling slightly") > Signed-off-by: Zhang Shurong <zhang_shurong@xxxxxxxxxxx> > --- This is a resend, a message in a shortlog to express why is welcome. If it's a ping, then no need to resend. > net/mac802154/iface.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/net/mac802154/iface.c b/net/mac802154/iface.c > index c0e2da5072be..c99b6e40a5db 100644 > --- a/net/mac802154/iface.c > +++ b/net/mac802154/iface.c > @@ -368,7 +368,6 @@ static int ieee802154_header_create(struct sk_buff *skb, > > memset(&hdr.fc, 0, sizeof(hdr.fc)); > hdr.fc.type = cb->type; > - hdr.fc.security_enabled = cb->secen; > hdr.fc.ack_request = cb->ackreq; > hdr.seq = atomic_inc_return(&dev->ieee802154_ptr->dsn) & 0xFF; > Thanks, Miquèl