348a8501e6
commit f9d87929d451d3e649699d0f1d74f71f77ad38f5 upstream. When the ucount code was refactored to create get_ucount it was missed that some of the contexts in which a rlimit is kept elevated can be the only reference to the user/ucount in the system. Ordinary ucount references exist in places that also have a reference to the user namspace, but in POSIX message queues, the SysV shm code, and the SIGPENDING code there is no independent user namespace reference. Inspection of the the user_namespace show no instance of circular references between struct ucounts and the user_namespace. So hold a reference from struct ucount to i's user_namespace to resolve this problem. Link: https://lore.kernel.org/lkml/YZV7Z+yXbsx9p3JN@fixkernel.com/ Reported-by: Qian Cai <quic_qiancai@quicinc.com> Reported-by: Mathias Krause <minipli@grsecurity.net> Tested-by: Mathias Krause <minipli@grsecurity.net> Reviewed-by: Mathias Krause <minipli@grsecurity.net> Reviewed-by: Alexey Gladkov <legion@kernel.org> Fixes: d64696905554 ("Reimplement RLIMIT_SIGPENDING on top of ucounts") Fixes: 6e52a9f0532f ("Reimplement RLIMIT_MSGQUEUE on top of ucounts") Fixes: d7c9e99aee48 ("Reimplement RLIMIT_MEMLOCK on top of ucounts") Cc: stable@vger.kernel.org Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> 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.