Messages in this thread | | | Date | Sun, 24 Aug 2008 18:23:31 +0300 | From | Pekka Enberg <> | Subject | Re: [Patch] Fix Buffer overflow in hfsplus with a corrupted image |
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Eric Sesterhenn wrote: > * 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);
Looks good to me.
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
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