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b42128078c
commit 800a7340ab upstream.
In copy_params(), the struct 'dm_ioctl' is first copied from the user
space buffer 'user' to 'param_kernel' and the field 'data_size' is
checked against 'minimum_data_size' (size of 'struct dm_ioctl' payload
up to its 'data' member). If the check fails, an error code EINVAL will be
returned. Otherwise, param_kernel->data_size is used to do a second copy,
which copies from the same user-space buffer to 'dmi'. After the second
copy, only 'dmi->data_size' is checked against 'param_kernel->data_size'.
Given that the buffer 'user' resides in the user space, a malicious
user-space process can race to change the content in the buffer between
the two copies. This way, the attacker can inject inconsistent data
into 'dmi' (versus previously validated 'param_kernel').
Fix redundant copying of 'minimum_data_size' from user-space buffer by
using the first copy stored in 'param_kernel'. Also remove the
'data_size' check after the second copy because it is now unnecessary.
Cc: stable@vger.kernel.org
Signed-off-by: Wenwen Wang <wang6495@umn.edu>
Signed-off-by: Mike Snitzer <snitzer@redhat.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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.