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[ Upstream commit 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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.