From e3c039e390523242d50961e6f97d21cab13b589f Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Thu, 4 Apr 2019 18:12:17 +0300 Subject: [PATCH] xen: Prevent buffer overflow in privcmd ioctl commit 42d8644bd77dd2d747e004e367cb0c895a606f39 upstream. 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 Reviewed-by: Boris Ostrovsky Signed-off-by: Juergen Gross [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- 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 da45f9fc19139..5876b28f93315 100644 --- a/arch/x86/include/asm/xen/hypercall.h +++ b/arch/x86/include/asm/xen/hypercall.h @@ -215,6 +215,9 @@ privcmd_call(unsigned call, __HYPERCALL_DECLS; __HYPERCALL_5ARG(a1, a2, a3, a4, a5); + if (call >= PAGE_SIZE / sizeof(hypercall_page[0])) + return -EINVAL; + stac(); asm volatile(CALL_NOSPEC : __HYPERCALL_5PARAM -- 2.47.2