KVM: fix the handling of dirty bitmaps to avoid overflows
Int is not long enough to store the size of a dirty bitmap.
This patch fixes this problem with the introduction of a wrapper
function to calculate the sizes of dirty bitmaps.
Note: in mark_page_dirty(), we have to consider the fact that
__set_bit() takes the offset as int, not long.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 73c5c2b..7f3c0a2 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -1802,7 +1802,8 @@
{
struct kvm_memory_slot *memslot;
int r, i;
- long n, base;
+ long base;
+ unsigned long n;
unsigned long *dirty_bitmap = (unsigned long *)(kvm->arch.vm_base +
offsetof(struct kvm_vm_data, kvm_mem_dirty_log));
@@ -1815,7 +1816,7 @@
if (!memslot->dirty_bitmap)
goto out;
- n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
+ n = kvm_dirty_bitmap_bytes(memslot);
base = memslot->base_gfn / BITS_PER_LONG;
for (i = 0; i < n/sizeof(long); ++i) {
@@ -1831,7 +1832,7 @@
struct kvm_dirty_log *log)
{
int r;
- int n;
+ unsigned long n;
struct kvm_memory_slot *memslot;
int is_dirty = 0;
@@ -1850,7 +1851,7 @@
if (is_dirty) {
kvm_flush_remote_tlbs(kvm);
memslot = &kvm->memslots->memslots[log->slot];
- n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
+ n = kvm_dirty_bitmap_bytes(memslot);
memset(memslot->dirty_bitmap, 0, n);
}
r = 0;
diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
index 25da07f..604af29 100644
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -1004,7 +1004,8 @@
struct kvm_vcpu *vcpu;
ulong ga, ga_end;
int is_dirty = 0;
- int r, n;
+ int r;
+ unsigned long n;
mutex_lock(&kvm->slots_lock);
@@ -1022,7 +1023,7 @@
kvm_for_each_vcpu(n, vcpu, kvm)
kvmppc_mmu_pte_pflush(vcpu, ga, ga_end);
- n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
+ n = kvm_dirty_bitmap_bytes(memslot);
memset(memslot->dirty_bitmap, 0, n);
}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9ad3d06..45aa90f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2612,8 +2612,9 @@
int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
struct kvm_dirty_log *log)
{
- int r, n, i;
+ int r, i;
struct kvm_memory_slot *memslot;
+ unsigned long n;
unsigned long is_dirty = 0;
unsigned long *dirty_bitmap = NULL;
@@ -2628,7 +2629,7 @@
if (!memslot->dirty_bitmap)
goto out;
- n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
+ n = kvm_dirty_bitmap_bytes(memslot);
r = -ENOMEM;
dirty_bitmap = vmalloc(n);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index a3fd0f9..9ad825e 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -119,6 +119,11 @@
int user_alloc;
};
+static inline unsigned long kvm_dirty_bitmap_bytes(struct kvm_memory_slot *memslot)
+{
+ return ALIGN(memslot->npages, BITS_PER_LONG) / 8;
+}
+
struct kvm_kernel_irq_routing_entry {
u32 gsi;
u32 type;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 5a0cd19..364daac 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -648,7 +648,7 @@
/* Allocate page dirty bitmap if needed */
if ((new.flags & KVM_MEM_LOG_DIRTY_PAGES) && !new.dirty_bitmap) {
- unsigned dirty_bytes = ALIGN(npages, BITS_PER_LONG) / 8;
+ unsigned long dirty_bytes = kvm_dirty_bitmap_bytes(&new);
new.dirty_bitmap = vmalloc(dirty_bytes);
if (!new.dirty_bitmap)
@@ -768,7 +768,7 @@
{
struct kvm_memory_slot *memslot;
int r, i;
- int n;
+ unsigned long n;
unsigned long any = 0;
r = -EINVAL;
@@ -780,7 +780,7 @@
if (!memslot->dirty_bitmap)
goto out;
- n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
+ n = kvm_dirty_bitmap_bytes(memslot);
for (i = 0; !any && i < n/sizeof(long); ++i)
any = memslot->dirty_bitmap[i];
@@ -1186,10 +1186,13 @@
memslot = gfn_to_memslot_unaliased(kvm, gfn);
if (memslot && memslot->dirty_bitmap) {
unsigned long rel_gfn = gfn - memslot->base_gfn;
+ unsigned long *p = memslot->dirty_bitmap +
+ rel_gfn / BITS_PER_LONG;
+ int offset = rel_gfn % BITS_PER_LONG;
/* avoid RMW */
- if (!generic_test_le_bit(rel_gfn, memslot->dirty_bitmap))
- generic___set_le_bit(rel_gfn, memslot->dirty_bitmap);
+ if (!generic_test_le_bit(offset, p))
+ generic___set_le_bit(offset, p);
}
}