d656fe49e3
In ethtool_get_rxnfc(), the object "info" is firstly copied from user-space. If the FLOW_RSS flag is set in the member field flow_type of "info" (and cmd is ETHTOOL_GRXFH), info needs to be copied again from user-space because FLOW_RSS is newer and has new definition, as mentioned in the comment. However, given that the user data resides in user-space, a malicious user can race to change the data after the first copy. By doing so, the user can inject inconsistent data. For example, in the second copy, the FLOW_RSS flag could be cleared in the field flow_type of "info". In the following execution, "info" will be used in the function ops->get_rxnfc(). Such inconsistent data can potentially lead to unexpected information leakage since ops->get_rxnfc() will prepare various types of data according to flow_type, and the prepared data will be eventually copied to user-space. This inconsistent data may also cause undefined behaviors based on how ops->get_rxnfc() is implemented. This patch simply re-verifies the flow_type field of "info" after the second copy. If the value is not as expected, an error code will be 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.