QgsRasterDataProvider.block() returns invalid QgsRasterBlock if requested block size exceeds a certain threshold

[janzandr]

What is the bug or the crash?

For any GDAL raster layer, the QgsRasterDataProvider.block() returns an invalid QgsRasterBlock, if requested block size exceeds a certain threshold.

Steps to reproduce the issue

1. Open a GDAL raster layer in QGIS, e.g. the dem.tif testdata: \QGIS3-master\tests\testdata\qgis_server_accesscontrol\dem.tif
2. In the Python Console execute:
   >>>iface.activeLayer().dataProvider().block(1, iface.mapCanvas().extent(), 65000, 50000).isValid()
False

Note that for slightly smaller block sizes, everything works fine:
>>>iface.activeLayer().dataProvider().block(1, iface.mapCanvas().extent(), 60000, 50000).isValid()
True

Versions

QGIS version
3.22.1-Białowieża
QGIS code revision
663dcf8
Qt version
5.15.2
Python version
3.9.5
GDAL/OGR version
3.4.0
PROJ version
8.2.0
EPSG Registry database version
v10.038 (2021-10-21)
GEOS version
3.10.0-CAPI-1.16.0
SQLite version
3.35.2
PDAL version
2.3.0
PostgreSQL client version
13.0
SpatiaLite version
5.0.1
QWT version
6.1.3
QScintilla2 version
2.11.5
OS version
Windows 10 Version 2009

Active Python plugins
BitFlagRenderer
0.4.20200817T093838.master
changeDataSource
3.1
DataPlotly
3.8.1
ee_plugin
0.0.4
force4qgis
1.0.1
InvisibleLayersAndGroups
2.1
rasterdataplotting
1.6.3
rastertimeseriesmanager
1.8
timeseriesviewerplugin
1.17.20210312T143004.master
zoomview
1.1.1
db_manager
0.1.20
grassprovider
2.12.99
MetaSearch
0.3.5
processing
2.12.99

Supported QGIS version

• I'm running a supported QGIS version according to the roadmap.

New profile

• I tried with a new QGIS profile

Additional context

No response

[janzandr]

Also note that GDAL can read raster of such size without a problem:

>>>iface.activeLayer().width()
65000
>>>iface.activeLayer().height()
46000
>>>gdal.Open(iface.activeLayer().source()).ReadAsArray().shape
(46000, 65000)

[jakimowb]

I can confirm this for OSGeo4W QGIS master. During initialization of the QgsRasterBlock the requested size_t = 6500000000 is too large and leads to long( size ) < 0 in *qgsMalloc( size_t size ).

void *qgsMalloc( size_t size )
{
  if ( size == 0 || long( size ) < 0 )
  {
    QgsDebugMsg( QStringLiteral( "Negative or zero size %1." ).arg( size ) );
    return nullptr;
  }
  void *p = malloc( size );
  if ( !p )
  {
    QgsDebugMsg( QStringLiteral( "Allocation of %1 bytes failed." ).arg( size ) );
  }
  return p;
}