2021-07-12 13:51:06

by Yue Haibing

Subject: [PATCH] nl802154: Fix type check in nl802154_new_interface()

We got this UBSAN warning:

UBSAN: shift-out-of-bounds in net/ieee802154/nl802154.c:920:44
shift exponent -1 is negative
CPU: 3 PID: 8258 Comm: repro Not tainted 5.13.0+ #222
Call Trace:
dump_stack_lvl+0x8d/0xcf
ubsan_epilogue+0xa/0x4e
__ubsan_handle_shift_out_of_bounds+0x161/0x182
nl802154_new_interface+0x3bf/0x3d0
genl_family_rcv_msg_doit.isra.15+0x12d/0x170
genl_rcv_msg+0x11a/0x240
netlink_rcv_skb+0x69/0x160
genl_rcv+0x24/0x40

NL802154_IFTYPE_UNSPEC is -1, so enum nl802154_iftype type now
is a signed integer, which is assigned by nla_get_u32 in
nl802154_new_interface(), this may cause type is negative and trigger
this warning.

Fixes: 65318680c97c ("ieee802154: add iftypes capability")
Signed-off-by: YueHaibing <[email protected]>
---
net/ieee802154/nl802154.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/ieee802154/nl802154.c b/net/ieee802154/nl802154.c
index 0cf2374..aab7ed4 100644
--- a/net/ieee802154/nl802154.c
+++ b/net/ieee802154/nl802154.c
@@ -915,7 +915,9 @@ static int nl802154_new_interface(struct sk_buff *skb, struct genl_info *info)

if (info->attrs[NL802154_ATTR_IFTYPE]) {
type = nla_get_u32(info->attrs[NL802154_ATTR_IFTYPE]);
- if (type > NL802154_IFTYPE_MAX ||
+ if (type < NL802154_IFTYPE_UNSPEC || type > NL802154_IFTYPE_MAX)
+ return -EINVAL;
+ if (type != NL802154_IFTYPE_UNSPEC &&
!(rdev->wpan_phy.supported.iftypes & BIT(type)))
return -EINVAL;
}
--
1.8.3.1

2021-07-13 13:34:15

by Alexander Aring

Subject: Re: [PATCH] nl802154: Fix type check in nl802154_new_interface()

Hi,

On Mon, 12 Jul 2021 at 09:49, YueHaibing <[email protected]> wrote:
>
> We got this UBSAN warning:
>
> UBSAN: shift-out-of-bounds in net/ieee802154/nl802154.c:920:44
> shift exponent -1 is negative
> CPU: 3 PID: 8258 Comm: repro Not tainted 5.13.0+ #222
> Call Trace:
> dump_stack_lvl+0x8d/0xcf
> ubsan_epilogue+0xa/0x4e
> __ubsan_handle_shift_out_of_bounds+0x161/0x182
> nl802154_new_interface+0x3bf/0x3d0
> genl_family_rcv_msg_doit.isra.15+0x12d/0x170
> genl_rcv_msg+0x11a/0x240
> netlink_rcv_skb+0x69/0x160
> genl_rcv+0x24/0x40
>
> NL802154_IFTYPE_UNSPEC is -1, so enum nl802154_iftype type now
> is a signed integer, which is assigned by nla_get_u32 in
> nl802154_new_interface(), this may cause type is negative and trigger
> this warning.

I think this is not the right fix, the fix is to change the UAPI that
NL802154_IFTYPE_UNSPEC fits into the netlink range of U32. I will
prepare a fix for that, it should still be backwards compatible.

- Alex