From 5e2e01666860178591d2616a71f88181ddedc732 Mon Sep 17 00:00:00 2001
From: Andrey Semashev <andrey.semashev@gmail.com>
Date: Thu, 21 Nov 2024 20:06:41 +0300
Subject: [PATCH] Fixed pointer arithmetics in wait state initialization on
 reallocation.

Fixes https://github.com/boostorg/atomic/issues/72.
---
 doc/changelog.qbk | 4 ++++
 src/lock_pool.cpp | 4 ++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/doc/changelog.qbk b/doc/changelog.qbk
index b245f8f..a5d8a74 100644
--- a/doc/changelog.qbk
+++ b/doc/changelog.qbk
@@ -7,6 +7,10 @@
 
 [section:changelog Changelog]
 
+[heading Boost 1.87]
+
+* Fixed initialization of atomic wait state list on memory reallocation. ([github_issue 72])
+
 [heading Boost 1.86]
 
 * Use [@https://man.openbsd.org/OpenBSD-6.2/futex.2 `futex(2)`] system call on OpenBSD since recent OpenBSD versions have removed support for `syscall(2)`.
diff --git a/src/lock_pool.cpp b/src/lock_pool.cpp
index adbea62..7e92546 100644
--- a/src/lock_pool.cpp
+++ b/src/lock_pool.cpp
@@ -1252,11 +1252,11 @@ wait_state_list::header* wait_state_list::allocate_buffer(std::size_t new_capaci
 
         const volatile void** old_a = get_atomic_pointers(old_header);
         std::memcpy(a, old_a, old_header->size * sizeof(const volatile void*));
-        std::memset(a + old_header->size * sizeof(const volatile void*), 0, (new_capacity - old_header->size) * sizeof(const volatile void*));
+        std::memset(a + old_header->size, 0, (new_capacity - old_header->size) * sizeof(const volatile void*));
 
         wait_state** old_w = get_wait_states(old_a, old_header->capacity);
         std::memcpy(w, old_w, old_header->capacity * sizeof(wait_state*)); // copy spare wait state pointers
-        std::memset(w + old_header->capacity * sizeof(wait_state*), 0, (new_capacity - old_header->capacity) * sizeof(wait_state*));
+        std::memset(w + old_header->capacity, 0, (new_capacity - old_header->capacity) * sizeof(wait_state*));
     }
     else
     {