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commit 9cb636b5f6a8cc6d1b50809ec8f8d33ae0c84c95 upstream. A race condition may occur if the user calls close() on another thread during a write() operation on the device node of the efi capsule. This is a race condition that occurs between the efi_capsule_write() and efi_capsule_flush() functions of efi_capsule_fops, which ultimately results in UAF. So, the page freeing process is modified to be done in efi_capsule_release() instead of efi_capsule_flush(). Cc: <stable@vger.kernel.org> # v4.9+ Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com> Link: https://lore.kernel.org/all/20220907102920.GA88602@ubuntu/ Signed-off-by: Ard Biesheuvel <ardb@kernel.org> 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.