Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2F338C282C4 for ; Mon, 4 Feb 2019 19:46:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 013F42087C for ; Mon, 4 Feb 2019 19:46:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726700AbfBDTqQ (ORCPT ); Mon, 4 Feb 2019 14:46:16 -0500 Received: from fieldses.org ([173.255.197.46]:51764 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725854AbfBDTqQ (ORCPT ); Mon, 4 Feb 2019 14:46:16 -0500 Received: by fieldses.org (Postfix, from userid 2815) id 827FC1C19; Mon, 4 Feb 2019 14:46:15 -0500 (EST) Date: Mon, 4 Feb 2019 14:46:15 -0500 To: Chuck Lever Cc: linux-nfs@vger.kernel.org, simo@redhat.com Subject: Re: [PATCH RFC 09/10] SUNRPC: Remove xdr_buf_trim() Message-ID: <20190204194615.GC1816@fieldses.org> References: <20190201195538.11389.96106.stgit@manet.1015granger.net> <20190201195814.11389.4023.stgit@manet.1015granger.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190201195814.11389.4023.stgit@manet.1015granger.net> User-Agent: Mutt/1.5.21 (2010-09-15) From: bfields@fieldses.org (J. Bruce Fields) Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Fri, Feb 01, 2019 at 02:58:14PM -0500, Chuck Lever wrote: > The key action of xdr_buf_trim() is that it shortens buf->len, the > length of the xdr_buf' content. The other actions -- shortening the > head, pages, and tail components -- are actually not necessary. In > some cases, changing the size of those components corrupts the RPC > message contained in the buffer. That's really burying the lede.... Is there an actual user-visible bug here? --b. > > Signed-off-by: Chuck Lever > --- > include/linux/sunrpc/xdr.h | 1 - > net/sunrpc/auth_gss/gss_krb5_wrap.c | 8 ++++--- > net/sunrpc/auth_gss/svcauth_gss.c | 2 +- > net/sunrpc/xdr.c | 41 ----------------------------------- > 4 files changed, 6 insertions(+), 46 deletions(-) > > diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h > index 69161cb..4ae398c 100644 > --- a/include/linux/sunrpc/xdr.h > +++ b/include/linux/sunrpc/xdr.h > @@ -183,7 +183,6 @@ static inline __be32 *xdr_encode_array(__be32 *p, const void *s, unsigned int le > extern void xdr_shift_buf(struct xdr_buf *, size_t); > extern void xdr_buf_from_iov(struct kvec *, struct xdr_buf *); > extern int xdr_buf_subsegment(struct xdr_buf *, struct xdr_buf *, unsigned int, unsigned int); > -extern void xdr_buf_trim(struct xdr_buf *, unsigned int); > extern int xdr_buf_read_netobj(struct xdr_buf *, struct xdr_netobj *, unsigned int); > extern int read_bytes_from_xdr_buf(struct xdr_buf *, unsigned int, void *, unsigned int); > extern int write_bytes_to_xdr_buf(struct xdr_buf *, unsigned int, void *, unsigned int); > diff --git a/net/sunrpc/auth_gss/gss_krb5_wrap.c b/net/sunrpc/auth_gss/gss_krb5_wrap.c > index 5cdde6c..14a0aff 100644 > --- a/net/sunrpc/auth_gss/gss_krb5_wrap.c > +++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c > @@ -570,14 +570,16 @@ static void rotate_left(u32 base, struct xdr_buf *buf, unsigned int shift) > */ > movelen = min_t(unsigned int, buf->head[0].iov_len, buf->len); > movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip; > - BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen > > - buf->head[0].iov_len); > + if (offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen > > + buf->head[0].iov_len) > + return GSS_S_FAILURE; > memmove(ptr, ptr + GSS_KRB5_TOK_HDR_LEN + headskip, movelen); > buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip; > buf->len -= GSS_KRB5_TOK_HDR_LEN + headskip; > > /* Trim off the trailing "extra count" and checksum blob */ > - xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip); > + buf->len -= ec + GSS_KRB5_TOK_HDR_LEN + tailskip; > + > return GSS_S_COMPLETE; > } > > diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c > index 152790e..f1aabab 100644 > --- a/net/sunrpc/auth_gss/svcauth_gss.c > +++ b/net/sunrpc/auth_gss/svcauth_gss.c > @@ -896,7 +896,7 @@ u32 svcauth_gss_flavor(struct auth_domain *dom) > if (svc_getnl(&buf->head[0]) != seq) > goto out; > /* trim off the mic and padding at the end before returning */ > - xdr_buf_trim(buf, round_up_to_quad(mic.len) + 4); > + buf->len -= 4 + round_up_to_quad(mic.len); > stat = 0; > out: > kfree(mic.data); > diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c > index 5f0aa53..4bce619 100644 > --- a/net/sunrpc/xdr.c > +++ b/net/sunrpc/xdr.c > @@ -1139,47 +1139,6 @@ void xdr_enter_page(struct xdr_stream *xdr, unsigned int len) > } > EXPORT_SYMBOL_GPL(xdr_buf_subsegment); > > -/** > - * xdr_buf_trim - lop at most "len" bytes off the end of "buf" > - * @buf: buf to be trimmed > - * @len: number of bytes to reduce "buf" by > - * > - * Trim an xdr_buf by the given number of bytes by fixing up the lengths. Note > - * that it's possible that we'll trim less than that amount if the xdr_buf is > - * too small, or if (for instance) it's all in the head and the parser has > - * already read too far into it. > - */ > -void xdr_buf_trim(struct xdr_buf *buf, unsigned int len) > -{ > - size_t cur; > - unsigned int trim = len; > - > - if (buf->tail[0].iov_len) { > - cur = min_t(size_t, buf->tail[0].iov_len, trim); > - buf->tail[0].iov_len -= cur; > - trim -= cur; > - if (!trim) > - goto fix_len; > - } > - > - if (buf->page_len) { > - cur = min_t(unsigned int, buf->page_len, trim); > - buf->page_len -= cur; > - trim -= cur; > - if (!trim) > - goto fix_len; > - } > - > - if (buf->head[0].iov_len) { > - cur = min_t(size_t, buf->head[0].iov_len, trim); > - buf->head[0].iov_len -= cur; > - trim -= cur; > - } > -fix_len: > - buf->len -= (len - trim); > -} > -EXPORT_SYMBOL_GPL(xdr_buf_trim); > - > static void __read_bytes_from_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len) > { > unsigned int this_len;