On 4/4/19 11:12 AM, Dan Carpenter wrote:
> The "call" variable comes from the user in privcmd_ioctl_hypercall().
> It's an offset into the hypercall_page[] which has (PAGE_SIZE / 32)
> elements. We need to put an upper bound on it to prevent an out of
> bounds access.
>
> Fixes: 1246ae0bb992 ("xen: add variable hypercall caller")
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
I am also adding stable@xxxxxxxxxxxxxxx
-boris
> ---
> arch/x86/include/asm/xen/hypercall.h | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/x86/include/asm/xen/hypercall.h b/arch/x86/include/asm/xen/hypercall.h
> index de6f0d59a24f..2863c2026655 100644
> --- a/arch/x86/include/asm/xen/hypercall.h
> +++ b/arch/x86/include/asm/xen/hypercall.h
> @@ -206,6 +206,9 @@ xen_single_call(unsigned int call,
> __HYPERCALL_DECLS;
> __HYPERCALL_5ARG(a1, a2, a3, a4, a5);
>
> + if (call >= PAGE_SIZE / sizeof(hypercall_page[0]))
> + return -EINVAL;
> +
> asm volatile(CALL_NOSPEC
> : __HYPERCALL_5PARAM
> : [thunk_target] "a" (&hypercall_page[call])
