From: Tony Luck <tony.luck@intel.com>
To: Martin Kletzander <nert.pinx@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>,
Reinette Chatre <reinette.chatre@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4] x86/resctrl: Avoid overflow in MB settings in bw_validate()
Date: Tue, 1 Oct 2024 13:22:33 -0700 [thread overview]
Message-ID: <ZvxaCamN7FP-TX2s@agluck-desk3.sc.intel.com> (raw)
In-Reply-To: <a8c3ef3e3d35924781280064a9f8c7dd2ee60565.1727782826.git.nert.pinx@gmail.com>
On Tue, Oct 01, 2024 at 01:43:56PM +0200, Martin Kletzander wrote:
> 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: 8205a078ba78 ("x86/intel_rdt/mba_sc: Add schemata support")
> Fixes: 6ce1560d35f6 ("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>
Reviewed-by: Tony Luck <tony.luck@intel.com>
-Tony
next prev parent reply other threads:[~2024-10-01 20:22 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-01 11:43 Martin Kletzander
2024-10-01 20:22 ` Tony Luck [this message]
2024-10-03 15:17 ` Reinette Chatre
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