Messages in this thread | | | Date | Tue, 13 Sep 2005 16:35:39 -0300 | From | Marcelo Tosatti <> | Subject | Re: [PATCH] nfs client, kernel 2.4.31: readlink result overflow |
| |
On Tue, Sep 13, 2005 at 02:52:44PM -0400, Assar wrote: > Hi, Marcelo. > > Marcelo Tosatti <marcelo.tosatti@cyclades.com> writes: > > > diff -u linux-2.4.31.orig/fs/nfs/nfs2xdr.c linux-2.4.31/fs/nfs/nfs2xdr.c > > > --- linux-2.4.31.orig/fs/nfs/nfs2xdr.c 2002-11-28 18:53:15.000000000 -0500 > > > +++ linux-2.4.31/fs/nfs/nfs2xdr.c 2005-09-12 16:12:30.000000000 -0400 > > > @@ -571,8 +571,8 @@ > > > strlen = (u32*)kmap(rcvbuf->pages[0]); > > > /* Convert length of symlink */ > > > len = ntohl(*strlen); > > > - if (len > rcvbuf->page_len) > > > - len = rcvbuf->page_len; > > > + if (len > rcvbuf->page_len - sizeof(*strlen) - 1) > > > + len = rcvbuf->page_len - sizeof(*strlen) - 1; > > > > So the problem is that the "len" variable encapsulated in (u32 *)rcvbuf->pages[0] > > does not account for its own length (4 bytes)? > > That's one problem. > > > If thats the reason, you don't need the "-1" there? > > It also writes a 0 byte. I think it looks like this: > > ---- ------------ - > len string... 0
If an overflow happens (len > rcvbuf->page_len) the last character will get truncated anyway, so there is no need for the "-1" AFAICS.
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |