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From "Thomas Neidhart (JIRA)" <>
Subject [jira] [Updated] (FILEUPLOAD-212) Insecure request size checking
Date Tue, 12 Mar 2013 07:39:12 GMT


Thomas Neidhart updated FILEUPLOAD-212:

    Attachment: FILEUPLOAD-212_test.patch

I worked on unit tests (see the attached patch) for the maxSize check and detected in the
process that a SizeException could be the cause of these "Stream ended unexpectedly" problems
some people have received.

This is due to the fact that in some internal methods of MultipartStream any IOException is
caught and re-thrown as MalformedStreamException. Any of the SizeExceptions is thrown inside
a FileUploadIOException (derived from IOException), to conform to the InputStream interface,
which is good, but we need to handle them separately and propagate the correct exception to
the user.

The patch also includes this change, please review.

The maxSize test also changes the MockHttpServletRequest to allow a readLimit: read at maximum
the given amount of bytes at a time, to better test the streaming API. Otherwise the full
buffer would be filled in one go.
> Insecure request size checking
> ------------------------------
>                 Key: FILEUPLOAD-212
>                 URL:
>             Project: Commons FileUpload
>          Issue Type: Bug
>    Affects Versions: 1.2.2
>         Environment: Default configuration default environment.
>            Reporter: Damian Kolasa
>            Assignee: Thomas Neidhart
>            Priority: Critical
>              Labels: max_upload_size, resource_depletion, security
>             Fix For: 1.3
>         Attachments: FILEUPLOAD-212_fix.patch, FILEUPLOAD-212_test.patch
>   Original Estimate: 48h
>  Remaining Estimate: 48h
> In FileUploadBase there is an issue when checking for upload request size, the check
is based on presence of Content-Length header in request and FALSE assumption that when present
it will represent the actual request size. Using this fact, attacker can supply request with
defined Content-Length of 60 and bypass file upload restrictions, which can lead to successful
Resource Depletion type attack. 
> IMHO by default file upload should return the LimitedInputStream implementation for file

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