From: James Houghton Date: Fri, 11 Jul 2025 00:17:42 +0000 (+0000) Subject: KVM: selftests: Fix signedness issue with vCPU mmap size check X-Git-Tag: v6.18-rc1~95^2~2^2~14 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a585b87614511e4272305bb5acf406f19f7dcade;p=thirdparty%2Fkernel%2Flinux.git KVM: selftests: Fix signedness issue with vCPU mmap size check Check that the return value of KVM_GET_VCPU_MMAP_SIZE is non-negative before comparing with sizeof(kvm_run). If KVM_GET_VCPU_MMAP_SIZE fails, it will return -1, and `-1 > sizeof(kvm_run)` is true, so the ASSERT passes. There are no other locations in tools/testing/selftests/kvm that make the same mistake. Signed-off-by: James Houghton Link: https://lore.kernel.org/r/20250711001742.1965347-1-jthoughton@google.com Signed-off-by: Sean Christopherson --- diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c index c3f5142b0a541..40e18034ac238 100644 --- a/tools/testing/selftests/kvm/lib/kvm_util.c +++ b/tools/testing/selftests/kvm/lib/kvm_util.c @@ -24,7 +24,7 @@ uint32_t guest_random_seed; struct guest_random_state guest_rng; static uint32_t last_guest_seed; -static int vcpu_mmap_sz(void); +static size_t vcpu_mmap_sz(void); int __open_path_or_exit(const char *path, int flags, const char *enoent_help) { @@ -1321,14 +1321,14 @@ void vm_guest_mem_fallocate(struct kvm_vm *vm, uint64_t base, uint64_t size, } /* Returns the size of a vCPU's kvm_run structure. */ -static int vcpu_mmap_sz(void) +static size_t vcpu_mmap_sz(void) { int dev_fd, ret; dev_fd = open_kvm_dev_path_or_exit(); ret = ioctl(dev_fd, KVM_GET_VCPU_MMAP_SIZE, NULL); - TEST_ASSERT(ret >= sizeof(struct kvm_run), + TEST_ASSERT(ret >= 0 && ret >= sizeof(struct kvm_run), KVM_IOCTL_ERROR(KVM_GET_VCPU_MMAP_SIZE, ret)); close(dev_fd); @@ -1369,7 +1369,7 @@ struct kvm_vcpu *__vm_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id) TEST_ASSERT_VM_VCPU_IOCTL(vcpu->fd >= 0, KVM_CREATE_VCPU, vcpu->fd, vm); TEST_ASSERT(vcpu_mmap_sz() >= sizeof(*vcpu->run), "vcpu mmap size " - "smaller than expected, vcpu_mmap_sz: %i expected_min: %zi", + "smaller than expected, vcpu_mmap_sz: %zi expected_min: %zi", vcpu_mmap_sz(), sizeof(*vcpu->run)); vcpu->run = (struct kvm_run *) mmap(NULL, vcpu_mmap_sz(), PROT_READ | PROT_WRITE, MAP_SHARED, vcpu->fd, 0);