In the Linux kernel, the following vulnerability has been resolved: KVM: s390: Fix length check __import_wp_info() struct kvm_hw_breakpoint::len is a __u64 that is fully controlled by user space

Overview

In the Linux kernel, the following vulnerability has been resolved:

KVM: s390: Fix length check __import_wp_info()

struct kvm_hw_breakpoint::len is a __u64 that is fully controlled by user space. This is then assigned to wp_info->len, which is an int. The bounds check is done on the truncated value while the allocation uses the untruncated one:

wp_info->len = bp_data->len;
[...]
if (wp_info->len < 0 || wp_info->len > MAX_WP_SIZE)
	return -EINVAL;

wp_info->old_data = kmalloc(bp_data->len, GFP_KERNEL_ACCOUNT);

Use the validated value for the allocation as intended. Without this fix userspace can trigger >4GB allocations which will fail and result in a WARN due to MAX_PAGE_ORDER.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.