[PATCH wpan] mac802154: fix uninit-value issue in ieee802154_header_create()

[Nikita Zhandarovich]

Syzkaller with KMSAN reported [1] a problem with uninitialized value
access in ieee802154_header_create().

The issue arises from a weird combination of cb->secen == 1 and
cb->secen_override == 0, while other required security parameters
are not found enabled in mac802154_set_header_security().

Ideally such case is expected to be caught by starting check at the
beginning of mac802154_set_header_security():

	if (!params.enabled && cb->secen_override && cb->secen)
		return -EINVAL;

However, since secen_override is zero, the function in question
passes this check and returns with success early, without having
set values to ieee802154_sechdr fields such as key_id_mode. This in
turn leads to uninitialized access of such values in
ieee802154_hdr_push_sechdr() and other places.

Fix this problem by only checking for secen value and presence of
security parameters (and ignoring secen_override). Exit early with
error if necessary requirements are not met.

[1]
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:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584
 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638
 __sys_sendmsg net/socket.c:2667 [inline]
 __do_sys_sendmsg net/socket.c:2676 [inline]
 __se_sys_sendmsg net/socket.c:2674 [inline]
 __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Local variable hdr created at:
 ieee802154_header_create+0x4e/0xc00 net/mac802154/iface.c:360
 wpan_dev_hard_header include/net/cfg802154.h:494 [inline]
 dgram_sendmsg+0xd1d/0x1500 net/ieee802154/socket.c:677

Fixes: f30be4d53cad ("mac802154: integrate llsec with wpan devices")
Reported-and-tested-by: syzbot+60a66d44892b66b56545@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=60a66d44892b66b56545
Signed-off-by: Nikita Zhandarovich <n.zhandarovich@xxxxxxxxxx>
---
P.S. Link to previous similar discussion:
https://lore.kernel.org/all/tencent_1C04CA8D66ADC45608D89687B4020B2A8706@xxxxxx/
P.P.S. This issue may affect stable versions, at least up to 6.1.

 net/mac802154/iface.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/mac802154/iface.c b/net/mac802154/iface.c
index c0e2da5072be..ad799d349625 100644
--- a/net/mac802154/iface.c
+++ b/net/mac802154/iface.c
@@ -328,7 +328,7 @@ static int mac802154_set_header_security(struct ieee802154_sub_if_data *sdata,
 
 	mac802154_llsec_get_params(&sdata->sec, &params);
 
-	if (!params.enabled && cb->secen_override && cb->secen)
+	if (!params.enabled && cb->secen)
 		return -EINVAL;
 	if (!params.enabled ||
 	    (cb->secen_override && !cb->secen) ||