45a4521dcb
__sock_map_delete() may be called from a tcp event such as unhash or
close from the following trace,
tcp_bpf_close()
tcp_bpf_remove()
sk_psock_unlink()
sock_map_delete_from_link()
__sock_map_delete()
In this case the sock lock is held but this only protects against
duplicate removals on the TCP side. If the map is free'd then we have
this trace,
sock_map_free
xchg() <- replaces map entry
sock_map_unref()
sk_psock_put()
sock_map_del_link()
The __sock_map_delete() call however uses a read, test, null over the
map entry which can result in both paths trying to free the map
entry.
To fix use xchg in TCP paths as well so we avoid having two references
to the same map entry.
Fixes: 604326b41a6fb ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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.