On 17.04.19 16:23, Eric Farman wrote: > > > On 4/17/19 3:49 AM, David Hildenbrand wrote: >> On 17.04.19 02:54, Eric Farman wrote: >>> 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@xxxxxxxxxxxxx> >>> --- >>> 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]; >> >> return kvm->arch.adapters[array_index_nospec(id, MAX_S390_IO_ADAPTERS)]; >> >> should exactly fit into a single line if I am not wrong. > > Yeah, just. As Paolo pointed out, that's not common usage. Though of > the four other hits I see, only one of them is the same as this > instance, in that "id" is passed as a variable and then we immediately > return with an array entry (even if NULL) rather than doing something > else in that function. So maybe all-in-one-line here is a little cleaner. > >> >>> } >>> >>> @@ -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); >> >> I dislike that we are modifying adapter_info here. Can you use a local >> variable instead? > > I guess, but adapter_info is a local variable too. So sanitization this > way seems fine to me. But if you dislike it more than I don't care, > I'll add another local variable. :) Oh right, I was confused, sorry. All fine. Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> -- Thanks, David / dhildenb
