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-rw-r--r--kernel/arch/arm/xen/hypercall.S15
1 files changed, 15 insertions, 0 deletions
diff --git a/kernel/arch/arm/xen/hypercall.S b/kernel/arch/arm/xen/hypercall.S
index f00e08075..10fd99c56 100644
--- a/kernel/arch/arm/xen/hypercall.S
+++ b/kernel/arch/arm/xen/hypercall.S
@@ -98,8 +98,23 @@ ENTRY(privcmd_call)
mov r1, r2
mov r2, r3
ldr r3, [sp, #8]
+ /*
+ * Privcmd calls are issued by the userspace. We need to allow the
+ * kernel to access the userspace memory before issuing the hypercall.
+ */
+ uaccess_enable r4
+
+ /* r4 is loaded now as we use it as scratch register before */
ldr r4, [sp, #4]
__HVC(XEN_IMM)
+
+ /*
+ * Disable userspace access from kernel. This is fine to do it
+ * unconditionally as no set_fs(KERNEL_DS)/set_fs(get_ds()) is
+ * called before.
+ */
+ uaccess_disable r4
+
ldm sp!, {r4}
ret lr
ENDPROC(privcmd_call);