diff mbox series

xen: Prevent buffer overflow in privcmd ioctl

Message ID 20190404151217.GA22334@kadam (mailing list archive)
State Accepted
Commit 42d8644bd77dd2d747e004e367cb0c895a606f39
Headers show
Series xen: Prevent buffer overflow in privcmd ioctl | expand

Commit Message

Dan Carpenter April 4, 2019, 3:12 p.m. UTC
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@oracle.com>
---
 arch/x86/include/asm/xen/hypercall.h | 3 +++
 1 file changed, 3 insertions(+)

Comments

Boris Ostrovsky April 4, 2019, 4:07 p.m. UTC | #1
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@oracle.com>

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

I am also adding stable@vger.kernel.org

-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])
Juergen Gross April 5, 2019, 6:47 a.m. UTC | #2
On 04/04/2019 17:12, 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@oracle.com>

Pushed to xen/tip.git for-linus-5.1b


Juergen
diff mbox series

Patch

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])