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5648b5e116
On 64bit platforms the MAC header is set to 0xffff on allocation and
also when a helper like skb_unset_mac_header() is called.
dev_parse_header may call skb_mac_header() which assumes valid mac offset:
BUG: KASAN: use-after-free in eth_header_parse+0x75/0x90
Read of size 6 at addr ffff8881075a5c05 by task nf-queue/1364
Call Trace:
memcpy+0x20/0x60
eth_header_parse+0x75/0x90
__nfqnl_enqueue_packet+0x1a61/0x3380
__nf_queue+0x597/0x1300
nf_queue+0xf/0x40
nf_hook_slow+0xed/0x190
nf_hook+0x184/0x440
ip_output+0x1c0/0x2a0
nf_reinject+0x26f/0x700
nfqnl_recv_verdict+0xa16/0x18b0
nfnetlink_rcv_msg+0x506/0xe70
The existing code only works if the skb has a mac header.
Fixes: 2c38de4c1f ("netfilter: fix looped (broad|multi)cast's MAC handling")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.