From: Mark Rutland <mark.rutland@arm.com> To: Robin Murphy <robin.murphy@arm.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>, Kees Cook <keescook@chromium.org>, Kernel Hardening <kernel-hardening@lists.openwall.com>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, James Morse <james.morse@arm.com>, Takahiro Akashi <akashi.takahiro@linaro.org>, Dave Martin <dave.martin@arm.com>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, Laura Abbott <labbott@fedoraproject.org> Subject: Re: [kernel-hardening] Re: [RFC PATCH 6/6] arm64: add VMAP_STACK and detect out-of-bounds SP Date: Fri, 14 Jul 2017 16:25:03 +0100 [thread overview] Message-ID: <20170714152503.GC16687@leverpostej> (raw) In-Reply-To: <8f805a19-19d1-3c97-c85b-510664d22dad@arm.com> On Fri, Jul 14, 2017 at 04:03:51PM +0100, Robin Murphy wrote: > On 14/07/17 15:39, Robin Murphy wrote: > > On 14/07/17 15:06, Mark Rutland wrote: > >> add sp, sp, x0 // sp = orig_sp + orig_x0 > >> sub x0, sp, x0 // x0 = orig_sp > >> < check > > >> sub x0, sp, x0 // x0 = orig_x0 > > > > Haven't you now forcibly cleared the top bit of x0 thanks to overflow? > > ...or maybe not. I still can't quite see it, but I suppose it must > cancel out somewhere, since Mr. Helpful C Program[1] has apparently > proven me mistaken :( > > I guess that means I approve! > > Robin. > > [1]: > #include <assert.h> > #include <stdint.h> > > int main(void) { > for (int i = 0; i < 256; i++) { > for (int j = 0; j < 256; j++) { > uint8_t x = i; > uint8_t y = j; > y = y + x; > x = y - x; > x = y - x; > y = y - x; > assert(x == i && y == j); > } > } > } I guess we have our first Tested-by for this series. :) Thanks for taking a look! Mark.
WARNING: multiple messages have this Message-ID (diff)
From: mark.rutland@arm.com (Mark Rutland) To: linux-arm-kernel@lists.infradead.org Subject: [kernel-hardening] Re: [RFC PATCH 6/6] arm64: add VMAP_STACK and detect out-of-bounds SP Date: Fri, 14 Jul 2017 16:25:03 +0100 [thread overview] Message-ID: <20170714152503.GC16687@leverpostej> (raw) In-Reply-To: <8f805a19-19d1-3c97-c85b-510664d22dad@arm.com> On Fri, Jul 14, 2017 at 04:03:51PM +0100, Robin Murphy wrote: > On 14/07/17 15:39, Robin Murphy wrote: > > On 14/07/17 15:06, Mark Rutland wrote: > >> add sp, sp, x0 // sp = orig_sp + orig_x0 > >> sub x0, sp, x0 // x0 = orig_sp > >> < check > > >> sub x0, sp, x0 // x0 = orig_x0 > > > > Haven't you now forcibly cleared the top bit of x0 thanks to overflow? > > ...or maybe not. I still can't quite see it, but I suppose it must > cancel out somewhere, since Mr. Helpful C Program[1] has apparently > proven me mistaken :( > > I guess that means I approve! > > Robin. > > [1]: > #include <assert.h> > #include <stdint.h> > > int main(void) { > for (int i = 0; i < 256; i++) { > for (int j = 0; j < 256; j++) { > uint8_t x = i; > uint8_t y = j; > y = y + x; > x = y - x; > x = y - x; > y = y - x; > assert(x == i && y == j); > } > } > } I guess we have our first Tested-by for this series. :) Thanks for taking a look! Mark.
next prev parent reply other threads:[~2017-07-14 15:26 UTC|newest] Thread overview: 110+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-07-12 22:32 [RFC PATCH 0/6] arm64: alternative VMAP_STACK implementation Mark Rutland 2017-07-12 22:32 ` [kernel-hardening] " Mark Rutland 2017-07-12 22:32 ` Mark Rutland 2017-07-12 22:32 ` [RFC PATCH 1/6] arm64: use tpidr_el1 for current, free sp_el0 Mark Rutland 2017-07-12 22:32 ` [kernel-hardening] " Mark Rutland 2017-07-12 22:32 ` Mark Rutland 2017-07-14 1:30 ` Will Deacon 2017-07-14 1:30 ` [kernel-hardening] " Will Deacon 2017-07-14 1:30 ` Will Deacon 2017-07-12 22:32 ` [RFC PATCH 2/6] arm64: avoid open-coding THREAD_SIZE{,_ORDER} Mark Rutland 2017-07-12 22:32 ` [kernel-hardening] " Mark Rutland 2017-07-12 22:32 ` Mark Rutland 2017-07-13 10:18 ` James Morse 2017-07-13 10:18 ` [kernel-hardening] " James Morse 2017-07-13 10:18 ` James Morse 2017-07-13 11:26 ` Mark Rutland 2017-07-13 11:26 ` [kernel-hardening] " Mark Rutland 2017-07-13 11:26 ` Mark Rutland 2017-07-12 22:33 ` [RFC PATCH 3/6] arm64: pad stacks to PAGE_SIZE for VMAP_STACK Mark Rutland 2017-07-12 22:33 ` [kernel-hardening] " Mark Rutland 2017-07-12 22:33 ` Mark Rutland 2017-07-12 22:33 ` [RFC PATCH 4/6] arm64: pass stack base to secondary_start_kernel Mark Rutland 2017-07-12 22:33 ` [kernel-hardening] " Mark Rutland 2017-07-12 22:33 ` Mark Rutland 2017-07-12 22:33 ` [RFC PATCH 5/6] arm64: keep track of current stack Mark Rutland 2017-07-12 22:33 ` [kernel-hardening] " Mark Rutland 2017-07-12 22:33 ` Mark Rutland 2017-07-12 22:33 ` [RFC PATCH 6/6] arm64: add VMAP_STACK and detect out-of-bounds SP Mark Rutland 2017-07-12 22:33 ` [kernel-hardening] " Mark Rutland 2017-07-12 22:33 ` Mark Rutland 2017-07-13 6:58 ` Ard Biesheuvel 2017-07-13 6:58 ` [kernel-hardening] " Ard Biesheuvel 2017-07-13 6:58 ` Ard Biesheuvel 2017-07-13 10:49 ` Mark Rutland 2017-07-13 10:49 ` [kernel-hardening] " Mark Rutland 2017-07-13 10:49 ` Mark Rutland 2017-07-13 11:49 ` Ard Biesheuvel 2017-07-13 11:49 ` [kernel-hardening] " Ard Biesheuvel 2017-07-13 11:49 ` Ard Biesheuvel 2017-07-13 16:10 ` Mark Rutland 2017-07-13 16:10 ` [kernel-hardening] " Mark Rutland 2017-07-13 16:10 ` Mark Rutland 2017-07-13 17:55 ` [kernel-hardening] " Mark Rutland 2017-07-13 17:55 ` Mark Rutland 2017-07-13 17:55 ` Mark Rutland 2017-07-13 18:28 ` Ard Biesheuvel 2017-07-13 18:28 ` Ard Biesheuvel 2017-07-13 18:28 ` Ard Biesheuvel 2017-07-14 10:32 ` Mark Rutland 2017-07-14 10:32 ` Mark Rutland 2017-07-14 10:32 ` Mark Rutland 2017-07-14 10:48 ` Ard Biesheuvel 2017-07-14 10:48 ` Ard Biesheuvel 2017-07-14 10:48 ` Ard Biesheuvel 2017-07-14 12:27 ` Ard Biesheuvel 2017-07-14 12:27 ` Ard Biesheuvel 2017-07-14 12:27 ` Ard Biesheuvel 2017-07-14 14:06 ` Mark Rutland 2017-07-14 14:06 ` Mark Rutland 2017-07-14 14:06 ` Mark Rutland 2017-07-14 14:14 ` Ard Biesheuvel 2017-07-14 14:14 ` Ard Biesheuvel 2017-07-14 14:14 ` Ard Biesheuvel 2017-07-14 14:39 ` Robin Murphy 2017-07-14 14:39 ` Robin Murphy 2017-07-14 14:39 ` Robin Murphy 2017-07-14 15:03 ` Robin Murphy 2017-07-14 15:03 ` Robin Murphy 2017-07-14 15:03 ` Robin Murphy 2017-07-14 15:15 ` Ard Biesheuvel 2017-07-14 15:15 ` Ard Biesheuvel 2017-07-14 15:15 ` Ard Biesheuvel 2017-07-14 15:25 ` Mark Rutland [this message] 2017-07-14 15:25 ` Mark Rutland 2017-07-14 15:25 ` Mark Rutland 2017-07-14 21:27 ` Mark Rutland 2017-07-14 21:27 ` Mark Rutland 2017-07-14 21:27 ` Mark Rutland 2017-07-16 0:03 ` Ard Biesheuvel 2017-07-16 0:03 ` Ard Biesheuvel 2017-07-16 0:03 ` Ard Biesheuvel 2017-07-18 21:53 ` Laura Abbott 2017-07-18 21:53 ` Laura Abbott 2017-07-18 21:53 ` Laura Abbott 2017-07-19 8:08 ` Ard Biesheuvel 2017-07-19 8:08 ` Ard Biesheuvel 2017-07-19 8:08 ` Ard Biesheuvel 2017-07-19 23:32 ` Laura Abbott 2017-07-19 23:32 ` Laura Abbott 2017-07-20 5:35 ` Ard Biesheuvel 2017-07-20 5:35 ` Ard Biesheuvel 2017-07-20 5:35 ` Ard Biesheuvel 2017-07-20 8:36 ` James Morse 2017-07-20 8:36 ` James Morse 2017-07-20 8:36 ` James Morse 2017-07-20 8:56 ` Ard Biesheuvel 2017-07-20 8:56 ` Ard Biesheuvel 2017-07-20 8:56 ` Ard Biesheuvel 2017-07-20 17:30 ` Ard Biesheuvel 2017-07-20 17:30 ` Ard Biesheuvel 2017-07-20 17:30 ` Ard Biesheuvel 2017-07-20 19:10 ` Laura Abbott 2017-07-20 19:10 ` Laura Abbott 2017-07-20 19:10 ` Laura Abbott 2017-07-14 12:52 ` Mark Rutland 2017-07-14 12:52 ` Mark Rutland 2017-07-14 12:52 ` Mark Rutland 2017-07-14 12:55 ` Ard Biesheuvel 2017-07-14 12:55 ` Ard Biesheuvel 2017-07-14 12:55 ` Ard Biesheuvel
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