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arm64: futex: Mask __user pointers prior to dereference

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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]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Will Deacon 2018-02-05 15:34:24 +00:00 committed by Greg Kroah-Hartman
parent 8223656109
commit 1cd969fdb4
1 changed files with 6 additions and 3 deletions
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9
arch/arm64/include/asm/futex.h
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@ -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"