Currently, if we need to check the value of the register defined by user
space, we should check it in set_user. However, some system registers
may use the same set_user (for example, almost all ID registers), which
make it difficult to validate the value defined by user space.
Introduce check_user to solve the problem. And apply check_user before
set_user to make sure that the value of register is valid.
Signed-off-by: zhanghailiang <zhang.zhanghailiang@xxxxxxxxxx>
Signed-off-by: Peng Liang <liangpeng10@xxxxxxxxxx>
---
arch/arm64/kvm/sys_regs.c | 7 +++++++
arch/arm64/kvm/sys_regs.h | 6 ++++++
2 files changed, 13 insertions(+)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 2b0fa8d5ac62..86ebb8093c3c 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -2684,6 +2684,7 @@ int kvm_arm_sys_reg_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg
{
const struct sys_reg_desc *r;
void __user *uaddr = (void __user *)(unsigned long)reg->addr;
+ int err;
if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_DEMUX)
return demux_c15_set(reg->id, uaddr);
@@ -2699,6 +2700,12 @@ int kvm_arm_sys_reg_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg
if (sysreg_hidden_from_user(vcpu, r))
return -ENOENT;
+ if (r->check_user) {
+ err = (r->check_user)(vcpu, r, reg, uaddr);
+ if (err)
+ return err;
+ }
+
if (r->set_user)
return (r->set_user)(vcpu, r, reg, uaddr);
diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h
index 5a6fc30f5989..9bce5e9a3490 100644
--- a/arch/arm64/kvm/sys_regs.h
+++ b/arch/arm64/kvm/sys_regs.h
@@ -53,6 +53,12 @@ struct sys_reg_desc {
const struct kvm_one_reg *reg, void __user *uaddr);
int (*set_user)(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
const struct kvm_one_reg *reg, void __user *uaddr);
+ /*
+ * Check the value userspace passed. It should return 0 on success and
+ * otherwise on failure.
+ */
+ int (*check_user)(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
+ const struct kvm_one_reg *reg, void __user *uaddr);
/* Return mask of REG_* runtime visibility overrides */
unsigned int (*visibility)(const struct kvm_vcpu *vcpu,
--
2.26.2
