From: Dave Martin <[email protected]> sve_reg_to_region() currently passes the result of vcpu_sve_state_size() to array_index_nospec(), effectively leading to a divide / modulo operation.
Currently the code bails out and returns -EINVAL if vcpu_sve_state_size() turns out to be zero, in order to avoid going ahead and attempting to divide by zero. This is reasonable, but it should only happen if the kernel contains some other bug that allowed this code to be reached without the vcpu having been properly initialised. To make it clear that this is a defence against bugs rather than something that the user should be able to trigger, this patch marks the check with WARN_ON(). Suggested-by: Andrew Jones <[email protected]> Signed-off-by: Dave Martin <[email protected]> Reviewed-by: Andrew Jones <[email protected]> Signed-off-by: Marc Zyngier <[email protected]> --- arch/arm64/kvm/guest.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c index e45a042c0628..73044e3f8706 100644 --- a/arch/arm64/kvm/guest.c +++ b/arch/arm64/kvm/guest.c @@ -371,7 +371,7 @@ static int sve_reg_to_region(struct sve_state_reg_region *region, } sve_state_size = vcpu_sve_state_size(vcpu); - if (!sve_state_size) + if (WARN_ON(!sve_state_size)) return -EINVAL; region->koffset = array_index_nospec(reqoffset, sve_state_size); -- 2.20.1 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
