2c05d88818
In cxgb_extension_ioctl(), the command of the ioctl is firstly copied from the user-space buffer 'useraddr' to 'cmd' and checked through the switch statement. If the command is not as expected, an error code EOPNOTSUPP is returned. In the following execution, i.e., the cases of the switch statement, the whole buffer of 'useraddr' is copied again to a specific data structure, according to what kind of command is requested. However, after the second copy, there is no re-check on the newly-copied command. Given that the buffer 'useraddr' is in the user space, a malicious user can race to change the command between the two copies. By doing so, the attacker can supply malicious data to the kernel and cause undefined behavior. This patch adds a re-check in each case of the switch statement if there is a second copy in that case, to re-check whether the command obtained in the second copy is the same as the one in the first copy. If not, an error code EINVAL is returned. Signed-off-by: Wenwen Wang <wang6495@umn.edu> Signed-off-by: David S. Miller <davem@davemloft.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.
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.