Messages in this thread | | | From | Gabriel Ryan <> | Date | Mon, 22 Aug 2022 12:23:41 -0400 | Subject | Re: data-race in pcpu_alloc / pcpu_nr_pages |
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Hi Steve,
Makes sense, thanks for taking the time to review this for us!
Best,
Gabe
On Thu, Aug 18, 2022 at 7:28 PM Steven Rostedt <rostedt@goodmis.org> wrote: > > On Thu, 18 Aug 2022 18:29:00 -0400 > Abhishek Shah <abhishek.shah@columbia.edu> wrote: > > > Hi all, > > > > We found a race involving the *pcpu_nr_populated *variable. We discovered > > that the racing variable is used in meminfo_proc_show > > <https://urldefense.proofpoint.com/v2/url?u=https-3A__elixir.bootlin.com_linux_v5.18-2Drc5_source_fs_proc_meminfo.c-23L123&d=DwICAg&c=009klHSCxuh5AI1vNQzSO0KGjl4nbi2Q0M1QLJX9BeE&r=EyAJYRJu01oaAhhVVY3o8zKgZvacDAXd_PNRtaqACCo&m=JaafDoHfUv9wBvITwFrxb8GW82J0sFuH-p1ItZM6jxU4b2c4UzG6SAgIIAX_vLz9&s=AHf4mjYOVq3qPnt65oFSjl4kztRIYFGagjntxAqUFWE&e= >, > > but we were not sure if there were other security-relevant implications of > > this race. Please let us know what you think. > > So you see that the number displayed in meminfo can be written to while > it's being read? As it's a long value, it is likely to be accurate (the > value before or after the update). pcpu_nr_pages() is only used to display > the number of pages in meminfo. > > I don't see any problem here. > > -- Steve
-- Gabriel Ryan PhD Candidate at Columbia University
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