Fix potential crash in color ramp shader

nyalldawson · nyalldawson · commit 237af60aa9d8 · 2018-07-20T16:00:21.000+10:00
Fixes #19445 (cherry-picked from f3650e6)
diff --git a/src/core/raster/qgscolorrampshader.cpp b/src/core/raster/qgscolorrampshader.cpp
@@ -346,6 +346,9 @@ bool QgsColorRampShader::shade( double value, int *returnRedValue, int *returnGr
     mLUTInitialized = true;
   }
 
+  if ( mLUT.empty() )
+    return false;
+
   // overflow indicates that value > maximum value + DOUBLE_DIFF_THRESHOLD
   // that way idx can point to the last valid item
   bool overflow = false;

Original file line number	Diff line number	Diff line change
`@@ -346,6 +346,9 @@ bool QgsColorRampShader::shade( double value, int returnRedValue, int returnGr`
`346`	`346`	`mLUTInitialized = true;`
`347`	`347`	`}`
`348`	`348`
	`349`	`+ if ( mLUT.empty() )`
	`350`	`+ return false;`
	`351`	`+`
`349`	`352`	`// overflow indicates that value > maximum value + DOUBLE_DIFF_THRESHOLD`
`350`	`353`	`// that way idx can point to the last valid item`
`351`	`354`	`bool overflow = false;`