Actually, it decompresses to a 5.8MB PNG. However, many graphics programs may choose to use three bytes per pixel when rendering the image and because it has incredibly large dimensions, this representation would take up 141GB of RAM.
I remember working with multi-megapixel images on systems with far less than 1MB of RAM, many years ago. Perhaps this is a good example of how more hardware resources can lead to them being wasted - the fact that RAM has grown so much that most images fit completely in it, has also meant programmers assuming they can do this for all images without a second thought when often all that's needed is a tiny subset of all the data.
Even if the image data is compressed, there's absolutely no need to keep all of it in memory - just decompress incrementally into a small, fixed-size buffer until you get to the "plaintext" position desired, ignoring everything before that. The fact that it's compressed also means that, with suitable algorithms, you can skip over huge spans at once - this is particularly easy to do with RLE and LZ - and the compression ratio actually boosts the speed of seeking to a specific position.
Currently, (hopefully...) no application is attempting to read entire video files into memory before processing them, but I wonder if that might change in the future as RAM becomes even bigger, and we'll start to get "video decompression bombs" instead?
Anyway, do you know some of these "better" graphics programs that actually behave this way, especially command line processing? I am interested in finding more of them.
EDIT: Okay, I have to add & admit that by "no excuse", I actually mean somewhat the opposite. ;) I mean that its possible to do streaming image processing on compressed formats, not that its trivial to do or as easy as decompressing the file in a single call. I just wish that programs would handle very large images more, and it sucks when they don't even though I know its possible. Especially programs intended for dealing with large images like Hugin. Now, I know its a PITA to tile & stream compressed formats because I've done it, but I'm sure I've written image I/O that decompresses the entire file to RAM 100x more frequently than anything that tiles and/or streams, because I've only handled tiling or streaming myself once, and it was harder. :P
It's ridiculous when the compression ratios are so absurd, like in this case.
Edit: skipping sections of the line to get to the region of interest is fine, I suppose, but what's really needed is a hierarchical quadtree-like organization of the storage, surely...
TIFF has specs for tiles, strips, subfiles, layers, etc. AFIAK, hardly anyone uses those, but they certainly exist.
JPEG is also composed of 8x8 squares and is easy to stream. The API has per-scanline read & write callbacks IIRC. But you're right; a very very wide one might be a case it can't deal with.
Now, go find an API/library for dealing with PNGs that allow you to pass in such a limit, let alone pass in a callback for dealing with violations. Go ahead. I'll wait.
(The Internet being what it is, if there is one, someone will pop up in a reply in five minutes citing it. If so, my compliments to the authors! But I think we can all agree that in general image APIs do not offer this control. In fact, in general, if you submit a patch to allow it, it would probably be rejected from most projects as unnecessarily complicating the API.)
This is the sort of thing that I mean when I say that we are so utterly buried by insecure coding practices that we can't hardly even perceive it around us. I should add this as another example in http://www.jerf.org/iri/post/2942 .
Not sure of Windows equivalent, Microsoft has deprecated Windows System Resource Manager, not sure of a good equivalent (except going fully to Linux).
That being said, even with these limits, it's undeniable that something like ImageMagick still has a very large attack surface (especially since it uses many third-party libraries), so it should run in its own heavily unprivileged or sandboxed process.
As you can see by reading that post as well, I'd also contend it really ought to be in the core API, not an optional thing that defaults to no limits. A sensible default could be imposed, too, though that turns out to be tricky to define the closer you look at it.
I'm actually about to add the same limits at my current job. It is an online slideshow builder, and most of the slides are scanned photographs. Last week someone uploaded a 11k x 17k JPG which hit us during a time of peak load and it caused quite a bit of trouble while the server was trying to build a thumbnail of it.
> I'd also contend it really ought to be in the core API, not an optional thing that defaults to no limits.
These limits really ought to be at a higher level, such as a ulimit on each apache process. In a large code base it requires too much effort to protect against every single avenue of potential accidental denial of service.
For example, at a previous job we had a lot of reports where the date range could be customized. This was fine for a long time, until a large client came along and ran his reports for the past five years. Since it was written in perl, it'd use up the RAM available on the system to generate the report, locking up the only webserver we had.
The article itself links to http://libpng.sourceforge.net/decompression_bombs.html
These new libpng versions do not impose any arbitrary limits, on the memory consumption and number of ancillary chunks, but they do allow applications to do so via the png_set_chunk_malloc_max() and png_set_chunk_cache_max() functions, respectively.
https://github.com/python-pillow/Pillow/blob/master/PIL/PngI...
While on vacation last week, I finally grokked that my relatively cheap Nikon camera is producing 6000x4000 images...that's about 100MB uncompressed. As a mobile app developer, I'm becoming painfully aware how images breaking the 25MB uncompressed line are breaking apps, with some still-in-use 256MB RAM iOS devices crashing when memory fills under normal usage plus a few instances of such large images (1-2 vacation photos can easily overwhelm available memory).