[PATCH] KVM: s390: Fix potential spectre warnings

Eric Farman
2019-04-17T00:54:14Z

Fix some warnings from smatch:

arch/s390/kvm/interrupt.c:2310 get_io_adapter() warn: potential spectre issue 'kvm->arch.adapters' [r] (local cap)
arch/s390/kvm/interrupt.c:2341 register_io_adapter() warn: potential spectre issue 'dev->kvm->arch.adapters' [w]

Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
A recent patch from Paolo [1] acted as a reminder (thanks, Christian!)
that I had one for the s390 KVM code after some code reviews [2].
Let's clean that up.

[1] https://patchwork.kernel.org/patch/10895463/
[2] https://patchwork.kernel.org/patch/10788565/#22484223
---
arch/s390/kvm/interrupt.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 82162867f378..bfd55ad34a3e 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -14,6 +14,7 @@
#include <linux/kvm_host.h>
#include <linux/hrtimer.h>
#include <linux/mmu_context.h>
+#include <linux/nospec.h>
#include <linux/signal.h>
#include <linux/slab.h>
#include <linux/bitmap.h>
@@ -2307,6 +2308,7 @@ static struct s390_io_adapter *get_io_adapter(struct kvm *kvm, unsigned int id)
{
if (id >= MAX_S390_IO_ADAPTERS)
return NULL;
+ id = array_index_nospec(id, MAX_S390_IO_ADAPTERS);
return kvm->arch.adapters[id];
}

@@ -2320,8 +2322,13 @@ static int register_io_adapter(struct kvm_device *dev,
(void __user *)attr->addr, sizeof(adapter_info)))
return -EFAULT;

- if ((adapter_info.id >= MAX_S390_IO_ADAPTERS) ||
- (dev->kvm->arch.adapters[adapter_info.id] != NULL))
+ if (adapter_info.id >= MAX_S390_IO_ADAPTERS)
+ return -EINVAL;
+
+ adapter_info.id = array_index_nospec(adapter_info.id,
+ MAX_S390_IO_ADAPTERS);
+
+ if (dev->kvm->arch.adapters[adapter_info.id] != NULL)
return -EINVAL;

adapter = kzalloc(sizeof(*adapter), GFP_KERNEL);
--
2.16.4