Messages in this thread | | | Date | Wed, 11 Dec 2019 01:23:34 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 2/2] perf/x86/intel/bts: Fix the use of page_private() |
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On Thu, Dec 05, 2019 at 05:28:53PM +0300, Alexander Shishkin wrote: > Commit > > 8062382c8dbe2 ("perf/x86/intel/bts: Add BTS PMU driver") > > uses page_private(page) without checking the PagePrivate(page) first, > which seems like a potential bug, considering that page->private aliases > with other stuff in struct page. > > Fix this by checking PagePrivate() first. > > Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> > Fixes: 8062382c8dbe2 ("perf/x86/intel/bts: Add BTS PMU driver") > --- > arch/x86/events/intel/bts.c | 14 +++++++++++--- > 1 file changed, 11 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c > index d53b4fb86d87..9e4da1c5a129 100644 > --- a/arch/x86/events/intel/bts.c > +++ b/arch/x86/events/intel/bts.c > @@ -63,9 +63,17 @@ struct bts_buffer { > > static struct pmu bts_pmu; > > +static int buf_nr_pages(struct page *page) > +{ > + if (!PagePrivate(page)) > + return 1; > + > + return 1 << page_private(page); > +} > + > static size_t buf_size(struct page *page) > { > - return 1 << (PAGE_SHIFT + page_private(page)); > + return 1 << (PAGE_SHIFT + buf_nr_pages(page));
Hurmph, shouldn't that be:
return buf_nr_pages(page) * PAGE_SIZE;
?
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