xen/arm: domain: Zero the per-vCPU cpu_info

A stack is allocated per vCPU to be used by Xen. The allocation is done
with alloc_xenheap_pages that does not zero the memory returned. However
the top of the stack is containing information that will be used to
store the initial state of the vCPU (see struct cpu_info). Some of the
fields may not be initialized and will lead to use/leak bits of previous
memory in some cases on the first run of vCPU (AFAICT this only happen on
vCPU0 for Dom0).

This is part of XSA-263.

Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index ec0f042bf7e4109990f270919fe7e2072ed37855..5a2a9a6b83b5c0e992a81eb674c0094958d8dc37 100644 (file)
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -550,6 +550,7 @@ int vcpu_initialise(struct vcpu *v)
     v->arch.cpu_info = (struct cpu_info *)(v->arch.stack
                                            + STACK_SIZE
                                            - sizeof(struct cpu_info));
+    memset(v->arch.cpu_info, 0, sizeof(*v->arch.cpu_info));
 
     memset(&v->arch.saved_context, 0, sizeof(v->arch.saved_context));
     v->arch.saved_context.sp = (register_t)v->arch.cpu_info;