librbd/cache/pwl/ssd: ensure first_{valid,free}_entry aren't bogus

Ensure first_{valid,free}_entry are inside the expected range when
scheduling root updates and decoding the root on recovery.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
(cherry picked from commit b46f81fbb22e67548e9825756da625d8e9017d10)

diff --git a/src/librbd/cache/pwl/ssd/WriteLog.cc b/src/librbd/cache/pwl/ssd/WriteLog.cc
index 56f73941f36c204cbe1424e0b4b9469cff1be21b..7e7fc42e865650f2de950fb847dc05d459d983e8 100644 (file)
--- a/src/librbd/cache/pwl/ssd/WriteLog.cc
+++ b/src/librbd/cache/pwl/ssd/WriteLog.cc
@@ -42,6 +42,16 @@ static bool is_valid_pool_root(const WriteLogPoolRoot& root) {
          root.first_free_entry % MIN_WRITE_ALLOC_SSD_SIZE == 0;
 }
 
+static bool is_valid_pool_root(const WriteLogPoolRoot& root) {
+  return root.pool_size % MIN_WRITE_ALLOC_SSD_SIZE == 0 &&
+         root.first_valid_entry >= DATA_RING_BUFFER_OFFSET &&
+         root.first_valid_entry < root.pool_size &&
+         root.first_valid_entry % MIN_WRITE_ALLOC_SSD_SIZE == 0 &&
+         root.first_free_entry >= DATA_RING_BUFFER_OFFSET &&
+         root.first_free_entry < root.pool_size &&
+         root.first_free_entry % MIN_WRITE_ALLOC_SSD_SIZE == 0;
+}
+
 template <typename I>
 Builder<AbstractWriteLog<I>>* WriteLog<I>::create_builder() {
   m_builderobj = new Builder<This>();