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@xxxxxxx>
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@xxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx> [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"
--
2.11.0