Messages in this thread | | | Date | Thu, 19 Apr 2018 12:33:06 +0300 | From | "Kirill A. Shutemov" <> | Subject | Re: [PATCH 0/6] arm64: untag user pointers passed to the kernel |
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On Wed, Apr 18, 2018 at 08:53:09PM +0200, Andrey Konovalov wrote: > Hi! > > arm64 has a feature called Top Byte Ignore, which allows to embed pointer > tags into the top byte of each pointer. Userspace programs (such as > HWASan, a memory debugging tool [1]) might use this feature and pass > tagged user pointers to the kernel through syscalls or other interfaces. > > This patch makes a few of the kernel interfaces accept tagged user > pointers. The kernel is already able to handle user faults with tagged > pointers and has the untagged_addr macro, which this patchset reuses. > > We're not trying to cover all possible ways the kernel accepts user > pointers in one patchset, so this one should be considered as a start.
How many changes do you anticipate?
This patchset looks small and reasonable, but I see a potential to become a boilerplate. Would we need to change every driver which implements ioctl() to strip these bits?
-- Kirill A. Shutemov
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