From b263230f8e80a5f209eb71f19f171059b64b8a9e Mon Sep 17 00:00:00 2001
From: Ilya Dryomov <idryomov@gmail.com>
Date: Fri, 21 May 2021 15:27:31 +0200
Subject: [PATCH] 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)
---
 src/librbd/cache/pwl/ssd/WriteLog.cc | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/librbd/cache/pwl/ssd/WriteLog.cc b/src/librbd/cache/pwl/ssd/WriteLog.cc
index 56f73941f36c2..7e7fc42e86565 100644
--- 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>();
-- 
2.39.5