Fix memory leak when calling GDALAllRegister() on a deferred loaded p…

…lugin that is absent from the system

Fixes rasterio/rasterio#3250

.github/workflows/asan/build.sh

@@ -23,6 +23,7 @@ cmake ${GDAL_SOURCE_DIR:=..} \
     -DUSE_CCACHE=ON \
     -DGDAL_USE_GEOTIFF_INTERNAL=ON \
     -DGDAL_USE_TIFF_INTERNAL=ON \
+    -DGDAL_ENABLE_DRIVER_PDF_PLUGIN=ON \
     -DGDAL_USE_LIBKML=OFF -DOGR_ENABLE_DRIVER_LIBKML=OFF \
     -DFileGDB_ROOT=/usr/local/FileGDB_API
 make -j$NPROC

.github/workflows/asan/test.sh

@@ -16,6 +16,14 @@ export PYTHONMALLOC=malloc
 gdalinfo autotest/gcore/data/byte.tif
 python3 -c "from osgeo import gdal; print('yes')"
 
+# Check fix for https://github.com/rasterio/rasterio/issues/3250
+mv ${GDAL_DRIVER_PATH}/gdal_PDF.so ${GDAL_DRIVER_PATH}/gdal_PDF.so.disabled
+echo "from osgeo import gdal" > register_many_times.py
+echo "for i in range(1000):" >> register_many_times.py
+echo "   gdal.AllRegister()" >> register_many_times.py
+python3 register_many_times.py
+mv ${GDAL_DRIVER_PATH}/gdal_PDF.so.disabled ${GDAL_DRIVER_PATH}/gdal_PDF.so
+
 cd autotest
 
 # Run each module in its own pytest process.

gcore/gdaldrivermanager.cpp

@@ -1668,6 +1668,19 @@ void GDALDriverManager::DeclareDeferredPluginDriver(
 
     if (osFullPath.empty())
     {
+        // Do not try to re-register a non-existent deferred plugin
+        // This would cause memory leaks in case of repeated calls to GDALAllRegister()
+        // Cf https://github.com/rasterio/rasterio/issues/3250
+        for (const auto &poDriver : m_aoHiddenDrivers)
+        {
+            if (EQUAL(poDriver->GetDescription(),
+                      poProxyDriver->GetDescription()))
+            {
+                delete poProxyDriver;
+                return;
+            }
+        }
+
         CPLDebug("GDAL",
                  "Proxy driver %s *not* registered due to %s not being found",
                  poProxyDriver->GetDescription(), pszPluginFileName);