Return-Path: Received: from mail-yw0-f193.google.com ([209.85.161.193]:45163 "EHLO mail-yw0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751981AbdJXSSz (ORCPT ); Tue, 24 Oct 2017 14:18:55 -0400 Received: by mail-yw0-f193.google.com with SMTP id j4so15877375ywb.2 for ; Tue, 24 Oct 2017 11:18:54 -0700 (PDT) Message-ID: <1508869132.4780.14.camel@redhat.com> Subject: Re: [PATCH] net: sunrpc: svcauth_gss: use BUG_ON instead of if condition followed by BUG From: Jeff Layton To: "J. Bruce Fields" , Weston Andros Adamson Cc: "Gustavo A. R. Silva" , Trond Myklebust , Anna Schumaker , "David S. Miller" , linux-nfs list , netdev@vger.kernel.org, "linux-kernel@vger.kernel.org" Date: Tue, 24 Oct 2017 14:18:52 -0400 In-Reply-To: <20171024175342.GA27853@fieldses.org> References: <20171023181635.GA25334@embeddedor.com> <20171023203135.GA21106@fieldses.org> <496D700A-E9D1-4745-B5DE-24BB9231A449@monkey.org> <20171024175342.GA27853@fieldses.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-nfs-owner@vger.kernel.org List-ID: On Tue, 2017-10-24 at 13:53 -0400, J. Bruce Fields wrote: > On Tue, Oct 24, 2017 at 01:26:49PM -0400, Weston Andros Adamson wrote: > > Is there a reason to BUG() in these places? Couldn't we WARN_ON_ONCE and return an error? > > I think the BUG() will just kill an nfsd thread that isn't holding any > interesting locks. > Not necessarily. If panic_on_oops is set (and it usually is in "production" setups), it'll crash the box there. > The failures look unlikely. (Except for that read_u32... return, I > wonder if we're missing a check there.) > Agreed, looks like you only hit an error if the read attempts to go out of bounds. In principle that shouldn't ever happen (and I haven't seen any reports of it). Still...I agree with Dros that it's better to handle this without oopsing if we can. We can return an error from either of those functions. A sane error and a WARN_ONCE would be better here. > --b. > > > > > -dros > > > > > On Oct 23, 2017, at 4:31 PM, J. Bruce Fields wrote: > > > > > > In the past we've avoided BUG_ON(X) where X might have side effects, on > > > the theory that it should actually be OK just to compile out BUG_ON()s. > > > Has that changed? > > > > > > In any case, I don't find that this improves readability; dropping. > > > > > > --b. > > > > > > On Mon, Oct 23, 2017 at 01:16:35PM -0500, Gustavo A. R. Silva wrote: > > > > Use BUG_ON instead of if condition followed by BUG. > > > > > > > > This issue was detected with the help of Coccinelle. > > > > > > > > Signed-off-by: Gustavo A. R. Silva > > > > --- > > > > net/sunrpc/auth_gss/svcauth_gss.c | 9 +++------ > > > > 1 file changed, 3 insertions(+), 6 deletions(-) > > > > > > > > diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c > > > > index 7b1ee5a..a10ce43 100644 > > > > --- a/net/sunrpc/auth_gss/svcauth_gss.c > > > > +++ b/net/sunrpc/auth_gss/svcauth_gss.c > > > > @@ -855,11 +855,9 @@ unwrap_integ_data(struct svc_rqst *rqstp, struct xdr_buf *buf, u32 seq, struct g > > > > return stat; > > > > if (integ_len > buf->len) > > > > return stat; > > > > - if (xdr_buf_subsegment(buf, &integ_buf, 0, integ_len)) > > > > - BUG(); > > > > + BUG_ON(xdr_buf_subsegment(buf, &integ_buf, 0, integ_len)); > > > > /* copy out mic... */ > > > > - if (read_u32_from_xdr_buf(buf, integ_len, &mic.len)) > > > > - BUG(); > > > > + BUG_ON(read_u32_from_xdr_buf(buf, integ_len, &mic.len)); > > > > if (mic.len > RPC_MAX_AUTH_SIZE) > > > > return stat; > > > > mic.data = kmalloc(mic.len, GFP_KERNEL); > > > > @@ -1611,8 +1609,7 @@ svcauth_gss_wrap_resp_integ(struct svc_rqst *rqstp) > > > > BUG_ON(integ_len % 4); > > > > *p++ = htonl(integ_len); > > > > *p++ = htonl(gc->gc_seq); > > > > - if (xdr_buf_subsegment(resbuf, &integ_buf, integ_offset, integ_len)) > > > > - BUG(); > > > > + BUG_ON(xdr_buf_subsegment(resbuf, &integ_buf, integ_offset, integ_len)); > > > > if (resbuf->tail[0].iov_base == NULL) { > > > > if (resbuf->head[0].iov_len + RPC_MAX_AUTH_SIZE > PAGE_SIZE) > > > > goto out_err; > > > > -- > > > > 2.7.4 > > > > > > -- > > > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > > > the body of a message to majordomo@vger.kernel.org > > > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Jeff Layton