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The resctrl schemata file supports specifying memory bandwidth associated with the Memory Bandwidth Allocation (MBA) feature via a percentage (this is the default) or bandwidth in MiBps (when resctrl is mounted with the "mba_MBps" option). The allowed range for the bandwidth percentage is from /sys/fs/resctrl/info/MB/min_bandwidth to 100, using a granularity of /sys/fs/resctrl/info/MB/bandwidth_gran. The supported range for the MiBps bandwidth is 0 to U32_MAX. There are two issues with parsing of MiBps memory bandwidth: * The user provided MiBps is mistakenly rounded up to the granularity that is unique to percentage input. * The user provided MiBps is parsed using unsigned long (thus accepting values up to ULONG_MAX), and then assigned to u32 that could result in overflow. Do not round up the MiBps value and parse user provided bandwidth as the u32 it is intended to be. Use the appropriate kstrtou32() that can detect out of range values. Fixes:8205a078ba("x86/intel_rdt/mba_sc: Add schemata support") Fixes:6ce1560d35("x86/resctrl: Switch over to the resctrl mbps_val list") Co-developed-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Martin Kletzander <nert.pinx@gmail.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com>
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 reStructuredText 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.