The AF_IEEE802154 sockaddr looks like this:
struct sockaddr_ieee802154 {
sa_family_t family; /* AF_IEEE802154 */
struct ieee802154_addr_sa addr;
};
struct ieee802154_addr_sa {
int addr_type;
u16 pan_id;
union {
u8 hwaddr[IEEE802154_ADDR_LEN];
u16 short_addr;
};
};
On most architectures there will be implicit structure padding here,
in two different places:
* In struct sockaddr_ieee802154, two bytes of padding between 'family'
(unsigned short) and 'addr', so that 'addr' starts on a four byte
boundary.
* In struct ieee802154_addr_sa, two bytes at the end of the structure,
to make the structure 16 bytes.
When calling recvmsg(2) on a PF_IEEE802154 SOCK_DGRAM socket, the
ieee802154 stack constructs a struct sockaddr_ieee802154 on the
kernel stack without clearing these padding fields, and, depending
on the addr_type, between four and ten bytes of uncleared kernel
stack will be copied to userspace.
We can't just insert two 'u16 __pad's in the right places and zero
those before copying an address to userspace, as not all architectures
insert this implicit padding -- from a quick test it seems that avr32,
cris and m68k don't insert this padding, while every other architecture
that I have cross compilers for does insert this padding.
The easiest way to plug the leak is to just memset the whole struct
sockaddr_ieee802154 before filling in the fields we want to fill in,
and that's what this patch does.
Cc: stable@vger.kernel.org
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Acked-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
8a70cefa30