c052797ac3
[ Upstream commit ff0a3a7d52ff7282dbd183e7fc29a1fe386b0c30 ]
Eric Dumazet says:
nf_conntrack_dccp_packet() has an unique:
dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &_dh);
And nothing more is 'pulled' from the packet, depending on the content.
dh->dccph_doff, and/or dh->dccph_x ...)
So dccp_ack_seq() is happily reading stuff past the _dh buffer.
BUG: KASAN: stack-out-of-bounds in nf_conntrack_dccp_packet+0x1134/0x11c0
Read of size 4 at addr ffff000128f66e0c by task syz-executor.2/29371
[..]
Fix this by increasing the stack buffer to also include room for
the extra sequence numbers and all the known dccp packet type headers,
then pull again after the initial validation of the basic header.
While at it, mark packets invalid that lack 48bit sequence bit but
where RFC says the type MUST use them.
Compile tested only.
v2: first skb_header_pointer() now needs to adjust the size to
only pull the generic header. (Eric)
Heads-up: I intend to remove dccp conntrack support later this year.
Fixes: 2bc780499aa3 ("[NETFILTER]: nf_conntrack: add DCCP protocol support")
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.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.