Messages in this thread Patch in this message | | | Date | Sun, 24 Aug 2008 17:24:54 +0200 | From | Eric Sesterhenn <> | Subject | Re: [Patch] Fix Buffer overflow in hfsplus with a corrupted image |
| |
* 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);
| |