From c792fd28b14ee2bcb1a0a15a8186388b0fae1486 Mon Sep 17 00:00:00 2001
From: Nicolas Werner <nicolas.werner@hotmail.de>
Date: Sat, 21 May 2022 15:21:14 +0200
Subject: [PATCH] Fix unsigned wraparound when creating one time keys

---
 src/ChatPage.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/ChatPage.cpp b/src/ChatPage.cpp
index cd7f3779..d4fbb801 100644
--- a/src/ChatPage.cpp
+++ b/src/ChatPage.cpp
@@ -1025,7 +1025,8 @@ ChatPage::ensureOneTimeKeyCount(const std::map<std::string, uint16_t> &counts,
           replace_fallback_key);
 
         if (count->second < MAX_ONETIME_KEYS || replace_fallback_key) {
-            const size_t nkeys = MAX_ONETIME_KEYS - count->second;
+            const size_t nkeys =
+              count->second < MAX_ONETIME_KEYS ? (MAX_ONETIME_KEYS - count->second) : 0;
 
             nhlog::crypto()->info("uploading {} {} keys", nkeys, mtx::crypto::SIGNED_CURVE25519);
             olm::client()->generate_one_time_keys(nkeys, replace_fallback_key);