Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753102AbdLESIq (ORCPT ); Tue, 5 Dec 2017 13:08:46 -0500 Received: from mail-ua0-f194.google.com ([209.85.217.194]:39344 "EHLO mail-ua0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752585AbdLESIp (ORCPT ); Tue, 5 Dec 2017 13:08:45 -0500 X-Google-Smtp-Source: AGs4zMaWdRDfxk4vUwTmAmb0i4pe5YaLPOFQYGnEt4pLj2tZQVfmsEY2tdW6AHu8HS1UIV0od283rtll1TZTzpZKkgM= MIME-Version: 1.0 In-Reply-To: <20171205175607.GD1701@mobilestation> References: <20171203191736.3399-1-fancer.lancer@gmail.com> <20171203191736.3399-4-fancer.lancer@gmail.com> <20171205175607.GD1701@mobilestation> From: Jon Mason Date: Tue, 5 Dec 2017 13:08:44 -0500 Message-ID: Subject: Re: [PATCH v2 03/15] NTB: Fix UB/bug in ntb_mw_get_align() To: Serge Semin Cc: Dave Jiang , "Hubbe, Allen" , "S-k, Shyam-sundar" , "Yu, Xiangliang" , Gary R Hook , Sergey.Semin@t-platforms.ru, linux-ntb , linux-kernel Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2317 Lines: 58 On Tue, Dec 5, 2017 at 12:56 PM, Serge Semin wrote: > On Tue, Dec 05, 2017 at 11:52:32AM -0500, Jon Mason wrote: >> On Sun, Dec 3, 2017 at 2:17 PM, Serge Semin wrote: >> > Simple (1 << pidx) operation causes undefined behaviour when >> > pidx >= 32. It must be casted to u64 to match the actual return >> > value of ntb_link_is_up() method, so to have all the possible >> > peer indexes covered and to get rid of undefined behaviour. >> > Additionally there are special macros in "linux/bitops.h" to perform >> > the bit-set-shift operations, so it's recommended to have them used >> > for proper bit setting. >> >> This looks good to me, but also seems like a bug fix. Please comment >> on if this is not noticed. >> > > The consequences of the bug isn't noticeable at the moment, but potentially > it can be seen on the devices like Switchtec (when multi-portness is finally > added). Anyway it's better to fix it now, than to wait for obvious bug. > Additionally as I said the originator of the code should have used BIT_ULL > instead of the pure bit shifting. This is more of a question of whether it should go into -stable and be outside this patch set. If this is impossible to ever hit, then including it here instead of fast tracking it in -stable is fine. Thanks, Jon > > Thanks, > -Sergey > >> Thanks, >> Jon >> >> > >> > Signed-off-by: Serge Semin >> > Reviewed-by: Logan Gunthorpe >> > --- >> > include/linux/ntb.h | 2 +- >> > 1 file changed, 1 insertion(+), 1 deletion(-) >> > >> > diff --git a/include/linux/ntb.h b/include/linux/ntb.h >> > index c1646f2c6344..488e586fb76c 100644 >> > --- a/include/linux/ntb.h >> > +++ b/include/linux/ntb.h >> > @@ -764,7 +764,7 @@ static inline int ntb_mw_get_align(struct ntb_dev *ntb, int pidx, int widx, >> > resource_size_t *size_align, >> > resource_size_t *size_max) >> > { >> > - if (!(ntb_link_is_up(ntb, NULL, NULL) & (1 << pidx))) >> > + if (!(ntb_link_is_up(ntb, NULL, NULL) & BIT_ULL(pidx))) >> > return -ENOTCONN; >> > >> > return ntb->ops->mw_get_align(ntb, pidx, widx, addr_align, size_align, >> > -- >> > 2.12.0 >> >