fdafed4599
GRE tunnel has its own header_ops, ipgre_header_ops, and sets it conditionally. When it is set, it assumes the outer IP header is already created before ipgre_xmit(). This is not true when we send packets through a raw packet socket, where L2 headers are supposed to be constructed by user. Packet socket calls dev_validate_header() to validate the header. But GRE tunnel does not set dev->hard_header_len, so that check can be simply bypassed, therefore uninit memory could be passed down to ipgre_xmit(). Similar for dev->needed_headroom. dev->hard_header_len is supposed to be the length of the header created by dev->header_ops->create(), so it should be used whenever header_ops is set, and dev->needed_headroom should be used when it is not set. Reported-and-tested-by: syzbot+4a2c52677a8a1aa283cb@syzkaller.appspotmail.com Cc: William Tu <u9012063@gmail.com> Acked-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Acked-by: Xie He <xie.he.0141@gmail.com> Signed-off-by: Jakub Kicinski <kuba@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.