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SubjectRe: [Patch] Fix Buffer overflow in hfsplus with a corrupted image
Hi Eric,

On Sun, Aug 24, 2008 at 4:07 PM, Eric Sesterhenn <snakebyte@gmx.de> wrote:
> when an hfsplus image gets corrupted it might happen that the catalog
> namelength field gets b0rked. If we mount such an image
> the memcpy() in hfsplus_cat_build_key_uni() writes more than the 255
> that fit in the name field. Depending on the size of the overwritten
> data, we either only get memory corruption or also trigger an oops like
> this:
>
> --- linux/fs/hfsplus/catalog.c.orig 2008-08-24 14:52:03.000000000 +0200
> +++ linux/fs/hfsplus/catalog.c 2008-08-24 14:54:15.000000000 +0200
> @@ -168,6 +168,11 @@ int hfsplus_find_cat(struct super_block
> return -EIO;
> }
>
> + if (be16_to_cpu(tmp.thread.nodeName.length) >= 127) {
> + printk(KERN_ERR "hfs: catalog name length corrupted\n");
> + return -EIO;
> + }

So, where does this 127 come from? I can only find reference to a
maximum length of 255 unicode characters (16 bits per character) in
the following technical note for HFS+ (see sections "HFS Plus Names"
and "Catalog Thread Records"):

http://developer.apple.com/technotes/tn/tn1150.html

Hmm?

Pekka


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