The calculation to get the per-slot dirty bitmap was incorrect leading
to a buffer overrun. Fix it by dividing the number of pages by
BITS_PER_LONG, since each element of the bitmap is a long and there is
one bit per page.
Fixes: 609e6202ea5f ("KVM: selftests: Support multiple slots in dirty_log_perf_test")
Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
---
tools/testing/selftests/kvm/dirty_log_perf_test.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
index 5ad9f2bc7369..0dd4626571e9 100644
--- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
@@ -118,6 +118,12 @@ static inline void disable_dirty_logging(struct kvm_vm *vm, int slots)
toggle_dirty_logging(vm, slots, false);
}
+static unsigned long *get_slot_bitmap(unsigned long *bitmap, uint64_t page_offset)
+{
+ /* Guaranteed to be evenly divisible by the TEST_ASSERT in run_test. */
+ return &bitmap[page_offset / BITS_PER_LONG];
+}
+
static void get_dirty_log(struct kvm_vm *vm, int slots, unsigned long *bitmap,
uint64_t nr_pages)
{
@@ -126,7 +132,8 @@ static void get_dirty_log(struct kvm_vm *vm, int slots, unsigned long *bitmap,
for (i = 0; i < slots; i++) {
int slot = PERF_TEST_MEM_SLOT_INDEX + i;
- unsigned long *slot_bitmap = bitmap + i * slot_pages;
+ uint64_t page_offset = slot_pages * i;
+ unsigned long *slot_bitmap = get_slot_bitmap(bitmap, page_offset);
kvm_vm_get_dirty_log(vm, slot, slot_bitmap);
}
@@ -140,7 +147,8 @@ static void clear_dirty_log(struct kvm_vm *vm, int slots, unsigned long *bitmap,
for (i = 0; i < slots; i++) {
int slot = PERF_TEST_MEM_SLOT_INDEX + i;
- unsigned long *slot_bitmap = bitmap + i * slot_pages;
+ uint64_t page_offset = slot_pages * i;
+ unsigned long *slot_bitmap = get_slot_bitmap(bitmap, page_offset);
kvm_vm_clear_dirty_log(vm, slot, slot_bitmap, 0, slot_pages);
}
@@ -172,6 +180,9 @@ static void run_test(enum vm_guest_mode mode, void *arg)
guest_num_pages = vm_adjust_num_guest_pages(mode, guest_num_pages);
host_num_pages = vm_num_host_pages(mode, guest_num_pages);
bmap = bitmap_alloc(host_num_pages);
+ TEST_ASSERT((host_num_pages / p->slots) % BITS_PER_LONG == 0,
+ "The number of pages per slot must be divisible by %d.",
+ BITS_PER_LONG);
if (dirty_log_manual_caps) {
cap.cap = KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2;
--
2.33.0.309.g3052b89438-goog
