4db4075f92
Commit 5f9c55c8066b ("ipv6: check return value of ipv6_skip_exthdr")
introduced an incorrect check, which leads to all ESP packets over
either TCPv6 or UDPv6 encapsulation being dropped. In this particular
case, offset is negative, since skb->data points to the ESP header in
the following chain of headers, while skb->network_header points to
the IPv6 header:
IPv6 | ext | ... | ext | UDP | ESP | ...
That doesn't seem to be a problem, especially considering that if we
reach esp6_input_done2, we're guaranteed to have a full set of headers
available (otherwise the packet would have been dropped earlier in the
stack). However, it means that the return value will (intentionally)
be negative. We can make the test more specific, as the expected
return value of ipv6_skip_exthdr will be the (negated) size of either
a UDP header, or a TCP header with possible options.
In the future, we should probably either make ipv6_skip_exthdr
explicitly accept negative offsets (and adjust its return value for
error cases), or make ipv6_skip_exthdr only take non-negative
offsets (and audit all callers).
Fixes: 5f9c55c8066b ("ipv6: check return value of ipv6_skip_exthdr")
Reported-by: Xiumei Mu <xmu@redhat.com>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
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.