On Thu, Apr 12, 2018 at 12:11:06PM +0100, Mark Rutland wrote:
> From: Will Deacon <will.deacon@xxxxxxx>
>
> commit 91b2d3442f6a44dce875670d702af22737ad5eff upstream.
>
> The arm64 futex code has some explicit dereferencing of user pointers
> where performing atomic operations in response to a futex command. This
> patch uses masking to limit any speculative futex operations to within
> the user address space.
>
> Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
> Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx> [v4.9 backport]
> Tested-by: Greg Hackmann <ghackmann@xxxxxxxxxx>
> ---
> arch/arm64/include/asm/futex.h | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/include/asm/futex.h b/arch/arm64/include/asm/futex.h
> index f2585cdd32c2..1d123dd01ee0 100644
> --- a/arch/arm64/include/asm/futex.h
> +++ b/arch/arm64/include/asm/futex.h
> @@ -51,13 +51,14 @@
> : "memory")
>
> static inline int
> -futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
> +futex_atomic_op_inuser (int encoded_op, u32 __user *_uaddr)
> {
> int op = (encoded_op >> 28) & 7;
> int cmp = (encoded_op >> 24) & 15;
> int oparg = (encoded_op << 8) >> 20;
> int cmparg = (encoded_op << 20) >> 20;
> int oldval = 0, ret, tmp;
> + u32 __user *uaddr = __uaccess_mask_ptr(_uaddr);
>
> if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
> oparg = 1 << oparg;
> @@ -109,15 +110,17 @@ futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
> }
>
> static inline int
> -futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
> +futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr,
> u32 oldval, u32 newval)
> {
> int ret = 0;
> u32 val, tmp;
> + u32 __user *uaddr;
>
> - if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
> + if (!access_ok(VERIFY_WRITE, _uaddr, sizeof(u32)))
> return -EFAULT;
>
> + uaddr = __uaccess_mask_ptr(_uaddr);
> asm volatile("// futex_atomic_cmpxchg_inatomic\n"
> ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
> " prfm pstl1strm, %2\n"
This patch doesn't apply at all as it conflicts with commit
d7c5f8c815466fc00785bbff20f25b39643abe01 which was commit 5f16a046f8e1
("arm64: futex: Fix undefined behaviour with FUTEX_OP_OPARG_SHIFT
usage") upstream.
Any chance you can provide a correct backport of this?
thanks,
greg k-h