From mboxrd@z Thu Jan 1 00:00:00 1970 From: kirill@shutemov.name (Kirill A. Shutemov) Date: Thu, 19 Apr 2018 12:33:06 +0300 Subject: [PATCH 0/6] arm64: untag user pointers passed to the kernel In-Reply-To: References: Message-ID: <20180419093306.rn5bz264nxsn7d7c@node.shutemov.name> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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