https://bugs.freedesktop.org/show_bug.cgi?id=32246
--- Comment #4 from Bryce Harrington bryce@canonical.com 2011-02-15 18:02:31 PST --- Created an attachment (id=43410) --> (https://bugs.freedesktop.org/attachment.cgi?id=43410) 0001-Check-for-null-pointer-in-mipmap-image-data.patch
It looks to me like this occurs when the calling application passes in a mipmap that has undefined image data (e.g. priv-target->Image[0][0]->Data == NULL in this case).
For the case where _mesa_is_format_compressed() is true, there is an ASSERT to catch that this is undefined, but there is no such check for the false case.
The attached patch adds such a check (a problem message rather than an assertion, though). Possibly it should be using _mesa_error() or perhaps an assert; I'm not certain.