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Fix crash: guard DrawingContext against a null image buffer (SIGSEGV) #2217

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Fix crash: guard DrawingContext against a null image buffer (SIGSEGV) #2217

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9 changes: 9 additions & 0 deletions submodules/Display/Source/GenerateImage.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -638,6 +638,15 @@ public class DrawingContext {
self.length = self.bytesPerRow * Int(scaledSize.height)

self.imageBuffer = ASCGImageBuffer(length: UInt(self.length))
if Int(bitPattern: self.imageBuffer.mutableBytes) == 0 {
// malloc(length) failed (e.g. an oversized allocation from a bad
// drawingSize). CGContext(data: nil, ...) below would silently
// succeed using CG's own internal buffer, masking the failure
// until the later memset(self.bytes, ...) writes through this
// null pointer and segfaults. Fail the init instead, matching
// the other guarded failure paths in this initializer.
return nil
}

if opaque {
self.bitmapInfo = DeviceGraphicsContextSettings.shared.opaqueBitmapInfo
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