Messages in this thread Patch in this message | | | Subject | Re: [PATCH] nfs client, kernel 2.4.31: readlink result overflow | From | Assar <> | Date | 14 Sep 2005 16:59:25 -0400 |
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Peter Staubach <staubach@redhat.com> writes: > Understand. I would recommend that the 2.4 kernel be modified to return > an error, since we are already modifying the area anyway.
Marcelo: what's your thought?
If you want to go that route, the patch below should do it.
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 2005-09-14 16:57:21.000000000 -0400 @@ -571,8 +571,11 @@ 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(u32) || len > NFS2_MAXPATHLEN) { + printk(KERN_WARNING "NFS: server returned giant symlink!\n"); + kunmap(rcvbuf->pages[0]); + return -ENAMETOOLONG; + } *strlen = len; /* NULL terminate the string we got */ string = (char *)(strlen + 1); diff -u linux-2.4.31.orig/fs/nfs/nfs3xdr.c linux-2.4.31/fs/nfs/nfs3xdr.c --- linux-2.4.31.orig/fs/nfs/nfs3xdr.c 2003-11-28 13:26:21.000000000 -0500 +++ linux-2.4.31/fs/nfs/nfs3xdr.c 2005-09-14 16:57:37.000000000 -0400 @@ -759,8 +759,11 @@ 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(u32)) { + printk(KERN_WARNING "NFS: server returned giant symlink!\n"); + kunmap(rcvbuf->pages[0]); + return -ENAMETOOLONG; + } *strlen = len; /* NULL terminate the string we got */ string = (char *)(strlen + 1); - 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/
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