From 8f7937ef3cf6ee2cfa481dab80ee6a515ad27bc1 Mon Sep 17 00:00:00 2001 From: Serhiy Storchaka Date: Fri, 22 May 2026 12:17:34 +0300 Subject: [PATCH] gh-137571: Protect against possible UnboundLocalError in gzip._GzipReader.read() (GH-150222) This has not been observed in practice, but we cannot be 100% sure that it will not happen with some weird gzip data. (cherry picked from commit 28eac9a7263ad8dcfa9b536aa238549131857e0f) Co-authored-by: Serhiy Storchaka --- Lib/gzip.py | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/Lib/gzip.py b/Lib/gzip.py index c00f51858de0f0..7514ad5bf24f26 100644 --- a/Lib/gzip.py +++ b/Lib/gzip.py @@ -575,10 +575,10 @@ def read(self, size=-1): # Read a chunk of data from the file if self._decompressor.needs_input: buf = self._fp.read(READ_BUFFER_SIZE) - uncompress = self._decompressor.decompress(buf, size) else: - uncompress = self._decompressor.decompress(b"", size) + buf = b"" + uncompress = self._decompressor.decompress(buf, size) if self._decompressor.unused_data != b"": # Prepend the already read bytes to the fileobj so they can # be seen by _read_eof() and _read_gzip_header()