> * Pekka Enberg (
penberg@cs.helsinki.fi) wrote:
>> 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?
>
> Ah, i missed that the name array is __be16, i somehow assumed it was a
> char array, and tried to account for the multiplication by 2 in
> hfsplus_cat_build_key_uni(). here is an updated fix.
>
> Signed-off-by: Eric Sesterhenn <snakebyte@gmx.de>
>
> --- 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) > 255) {
> + printk(KERN_ERR "hfs: catalog name length corrupted\n");
> + return -EIO;
> + }
> +
> hfsplus_cat_build_key_uni(fd->search_key, be32_to_cpu(tmp.thread.parentID),
> &tmp.thread.nodeName);
> return hfs_brec_find(fd);
