From 42d7465cbabb4d0be58b166bd374d1d1d8976162 Mon Sep 17 00:00:00 2001
From: Vladimir Golovnev <glassez@yandex.ru>
Date: Sat, 28 Oct 2023 10:41:53 +0300
Subject: [PATCH] Prevent crash due to race condition when adding magnet link

PR #19792.
Closes #19780.
Closes #19790.
---
 src/base/bittorrent/sessionimpl.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/base/bittorrent/sessionimpl.cpp b/src/base/bittorrent/sessionimpl.cpp
index aeaa54698..e1011777c 100644
--- a/src/base/bittorrent/sessionimpl.cpp
+++ b/src/base/bittorrent/sessionimpl.cpp
@@ -2435,6 +2435,11 @@ bool SessionImpl::cancelDownloadMetadata(const TorrentID &id)
         return false;
 
     const lt::torrent_handle nativeHandle = downloadedMetadataIter.value();
+    m_downloadedMetadata.erase(downloadedMetadataIter);
+
+    if (!nativeHandle.is_valid())
+        return true;
+
 #ifdef QBT_USES_LIBTORRENT2
     const InfoHash infoHash {nativeHandle.info_hashes()};
     if (infoHash.isHybrid())
@@ -2445,7 +2450,7 @@ bool SessionImpl::cancelDownloadMetadata(const TorrentID &id)
         m_downloadedMetadata.remove((altID == downloadedMetadataIter.key()) ? id : altID);
     }
 #endif
-    m_downloadedMetadata.erase(downloadedMetadataIter);
+
     m_nativeSession->remove_torrent(nativeHandle, lt::session::delete_files);
     return true;
 }