to den 22.09.2005 Klokka 13:14 (-0300) skreiv Marcelo Tosatti:
> commit 87e03738fc15dc3ea4acde3a5dcb5f84b6b6152b
> tree be323c0a65d7e380ad04cad1c3a80015a82056dd
> parent bb52ef60b5caa8f973523eda15d3c3941f298e63
> author Assar <[email protected]> Wed, 14 Sep 2005 16:59:25 -0400
> committer Marcelo Tosatti <[email protected]> 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) {
Shouldn't that be
if (len > rcvbuf->page_len - sizeof(u32) || len > NFS2_MAXPATHLEN)
? As long as we use page_len == PAGE_SIZE, we probably don't care, but
if someone some day decides to set a different value for page_len, then
we want to make sure that we don't end up overflowing the buffer when we
NUL-terminate.
> + printk(KERN_WARNING "NFS: server returned giant symlink!\n");
Please make this a dprintk().
> + 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)) {
Ditto.
> + printk(KERN_WARNING "NFS: server returned giant symlink!\n");
...and ditto.
> + kunmap(rcvbuf->pages[0]);
> + return -ENAMETOOLONG;
> + }
> *strlen = len;
> /* NULL terminate the string we got */
> string = (char *)(strlen + 1);
Cheers,
Trond
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