671331c11c
[ Upstream commit bee348907d19d654e8524d3a946dcd25b693aa7e ] When an XDP program is installed, tun_build_skb() grabs a reference to the current page fragment page if the program returns XDP_REDIRECT or XDP_TX. However, since tun_xdp_act() passes through negative return values from the XDP program, it is possible to trigger the error path by mistake and accidentally drop a reference to the fragments page without taking one, leading to a spurious free. This is believed to be the cause of some KASAN use-after-free reports from syzbot [1], although without a reproducer it is not possible to confirm whether this patch fixes the problem. Ensure that we only drop a reference to the fragments page if the XDP transmit or redirect operations actually fail. [1] https://syzkaller.appspot.com/bug?id=e76a6af1be4acd727ff6bbca669833f98cbf5d95 Cc: "David S. Miller" <davem@davemloft.net> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> CC: Eric Dumazet <edumazet@google.com> Acked-by: Jason Wang <jasowang@redhat.com> Fixes: 8ae1aff0b331 ("tuntap: split out XDP logic") Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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.