On Tue, Apr 17, 2018 at 02:10:03PM +0200, Greg KH wrote:
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?
The below is rebased atop of the conflicting patch (I based it on v4.9.94). Luckily it's just a trivial conflict in the function prototype.
Is this the right way to resend this?
Thanks, Mark.
---->8----
From 4ff73a6f286a8438529462391eca262b6772e9c1 Mon Sep 17 00:00:00 2001
From: Will Deacon will.deacon@arm.com Date: Mon, 5 Feb 2018 15:34:24 +0000 Subject: [PATCH] arm64: futex: Mask __user pointers prior to dereference
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@arm.com Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Mark Rutland mark.rutland@arm.com [v4.9 backport] --- 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 20dcb196b240..4e5f36a804b4 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(unsigned int encoded_op, u32 __user *uaddr) +futex_atomic_op_inuser(unsigned int encoded_op, u32 __user *_uaddr) { int op = (encoded_op >> 28) & 7; int cmp = (encoded_op >> 24) & 15; int oparg = (int)(encoded_op << 8) >> 20; int cmparg = (int)(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 = 1U << (oparg & 0x1f); @@ -109,15 +110,17 @@ futex_atomic_op_inuser(unsigned 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"