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arm64: futex: Mask __user pointers prior to dereference

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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 <[email protected]>
Signed-off-by: Catalin Marinas <[email protected]>
This commit is contained in:
Will Deacon 2018-02-05 15:34:24 +00:00 • committed by Catalin Marinas
commit 91b2d3442f
1 changed files with 6 additions and 3 deletions
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9
arch/arm64/include/asm/futex.h
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@ -48,9 +48,10 @@ do { \
} while (0)
static inline int
arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr)
{
int oldval = 0, ret, tmp;
u32 __user *uaddr = __uaccess_mask_ptr(_uaddr);
pagefault_disable();
@ -88,15 +89,17 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, 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);
uaccess_enable();
asm volatile("// futex_atomic_cmpxchg_inatomic\n"
" prfm pstl1strm, %2\n"