DRMBackend: Fix NULL dereference in drm_prepare_liftoff()

digetx · misyltoad · commit c2fecc58da0e · 2025-12-20T20:48:54.000Z
Fix gamescope crashing with a NULL dereference in drm_prepare_liftoff(). Fixes: 8f82d51 ("backend: Add support for deferred backends") Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
diff --git a/src/Backends/DRMBackend.cpp b/src/Backends/DRMBackend.cpp
@@ -2561,7 +2561,7 @@ drm_prepare_liftoff( struct drm_t *drm, const struct FrameInfo_t *frameInfo, boo
 		if ( i < frameInfo->layerCount )
 		{
 			const FrameInfo_t::Layer_t *pLayer = &frameInfo->layers[ i ];
-			gamescope::CDRMFb *pDrmFb = static_cast<gamescope::CDRMFb *>( pLayer->tex ? pLayer->tex->GetBackendFb()->Unwrap() : nullptr );
+			gamescope::CDRMFb *pDrmFb = static_cast<gamescope::CDRMFb *>( (pLayer->tex && pLayer->tex->GetBackendFb()) ? pLayer->tex->GetBackendFb()->Unwrap() : nullptr );
 
 			if ( pDrmFb == nullptr )
 			{

Original file line number	Diff line number	Diff line change
`@@ -2561,7 +2561,7 @@ drm_prepare_liftoff( struct drm_t drm, const struct FrameInfo_t frameInfo, boo`
`2561`	`2561`	`if ( i < frameInfo->layerCount )`
`2562`	`2562`	`{`
`2563`	`2563`	`const FrameInfo_t::Layer_t *pLayer = &frameInfo->layers[ i ];`
`2564`		`- gamescope::CDRMFb pDrmFb = static_cast<gamescope::CDRMFb >( pLayer->tex ? pLayer->tex->GetBackendFb()->Unwrap() : nullptr );`
	`2564`	`+ gamescope::CDRMFb pDrmFb = static_cast<gamescope::CDRMFb >( (pLayer->tex && pLayer->tex->GetBackendFb()) ? pLayer->tex->GetBackendFb()->Unwrap() : nullptr );`
`2565`	`2565`
`2566`	`2566`	`if ( pDrmFb == nullptr )`
`2567`	`2567`	`{`