[PATCH] nfs client: handle long symlinks properly

[Marcelo Tosatti <marcelo.tosatti@cyclades.com>]

commit 87e03738fc15dc3ea4acde3a5dcb5f84b6b6152b
tree be323c0a65d7e380ad04cad1c3a80015a82056dd
parent bb52ef60b5caa8f973523eda15d3c3941f298e63
author Assar <assar@permabit.com> Wed, 14 Sep 2005 16:59:25 -0400
committer Marcelo Tosatti <marcelo@dmt.cnet> Thu, 22 Sep 2005 13:11:18 -0300

    [PATCH] nfs client: handle long symlinks properly

    In 2.4.31, the v2/3 nfs readlink accepts too long symlinks.
    I have tested this by having a server return long symlinks.

diff --git a/fs/nfs/nfs2xdr.c b/fs/nfs/nfs2xdr.c
--- a/fs/nfs/nfs2xdr.c
+++ b/fs/nfs/nfs2xdr.c
@@ -571,8 +571,11 @@ nfs_xdr_readlinkres(struct rpc_rqst *req
        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 --git a/fs/nfs/nfs3xdr.c b/fs/nfs/nfs3xdr.c
--- a/fs/nfs/nfs3xdr.c
+++ b/fs/nfs/nfs3xdr.c
@@ -759,8 +759,11 @@ nfs3_xdr_readlinkres(struct rpc_rqst *re
        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);

-
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