5.1.0-1ubuntu0.6 on bionic (python2) can fail on Parser.feed(data) due to OSError

[Tom Haddon]

The python2 version of pillow in bionic (python-pil 5.1.0-1ubuntu0.6) included debian/patches/CVE-2021-28675.patch includes has the following:

```
--- a/src/PIL/ImageFile.py
+++ b/src/PIL/ImageFile.py
@@ -522,12 +522,18 @@ def _safe_read(fp, size):

     :param fp: File handle. Must implement a <b>read</b> method.
     :param size: Number of bytes to read.
- :returns: A string containing up to <i>size</i> bytes of data.
+ :returns: A string containing <i>size</i> bytes of data.
+
+ Raises an OSError if the file is truncated and the read can not be completed
+
     """
     if size <= 0:
         return b""
     if size <= SAFEBLOCK:
- return fp.read(size)
+ data = fp.read(size)
+ if len(data) < size:
+ raise OSError("Truncated File Read")
+ return data
     data = []
     while size > 0:
         block = fp.read(min(size, SAFEBLOCK))
@@ -535,6 +541,8 @@ def _safe_read(fp, size):
             break
         data.append(block)
         size -= len(block)
+ if sum(len(d) for d in data) < size:
+ raise OSError("Truncated File Read")
     return b"".join(data)
```

However, further up in the file in the `feed` method we have:

```
# attempt to open this file
try:
    with io.BytesIO(self.data) as fp:
        im = Image.open(fp)
except IOError:
    # traceback.print_exc()
    pass # not enough data
```

In the python3 version of this file the IOError has already been changed to OSError but not so here.

In my local copy of /usr/lib/python2.7/dist-packages/PIL/ImageFile.py I've changed line 392 from `except IOError:` to `except (IOError, OSError):` and I can confirm this has fixed the issues I've been seeing since the release of 5.1.0-1ubuntu0.6 (tracebacks with `OSError("Truncated File Read")`).

I've tried running the test suite locally (with `make test`) to submit a patch, but I'm getting lots of unrelated failures in tests (missing pytest imports, file comparisons not matching, etc.). Happy to provide more detail on that if appropriate.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Tom Haddon (mthaddon)]

This is still an issue with 5.1.0-1ubuntu0.7 of python-pil on bionic.