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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 round 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. >> > > Great, can I use your commit message then?  I wouldn't be able to write > it as nicely =) Sure. > >> >> This needs "Fixes" tags. Looks like the following are appropriate: >> Fixes: 8205a078ba78 ("x86/intel_rdt/mba_sc: Add schemata support") >> Fixes: 6ce1560d35f6 ("x86/resctrl: Switch over to the resctrl mbps_val list") >> > > It seems to me like this should've been handled in commit 8205a078ba78 > ("x86/intel_rdt/mba_sc: Add schemata support") which added support for > mba_sc and kept the rounding up of the value while skipping the range > validation. Right. That commit additionally suffers from the overflow problem by, after rounding up the value, assigning the unsigned long result to a u32 (struct rdt_domain.newctrl). I added 6ce1560d35f6, not because of the rounding issue, but instead of it switching the destination of assignment to struct rdt_domain.mbps_val, which also happens to be a u32. I included both commits with the goal to help anybody that may be looking at backporting this fix. Reinette