From mboxrd@z Thu Jan 1 00:00:00 1970 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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 581F7C433FF for ; Tue, 30 Jul 2019 17:22:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2C4242089E for ; Tue, 30 Jul 2019 17:22:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730687AbfG3RWx (ORCPT ); Tue, 30 Jul 2019 13:22:53 -0400 Received: from mx2.suse.de ([195.135.220.15]:44800 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727532AbfG3RWw (ORCPT ); Tue, 30 Jul 2019 13:22:52 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 724C9AF77; Tue, 30 Jul 2019 17:22:49 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id DA3681E4370; Tue, 30 Jul 2019 19:22:48 +0200 (CEST) Date: Tue, 30 Jul 2019 19:22:48 +0200 From: Jan Kara To: Qian Cai Cc: akpm@linux-foundation.org, tobin@kernel.org, rostedt@goodmis.org, mingo@redhat.com, tj@kernel.org, dchinner@redhat.com, fengguang.wu@intel.com, jack@suse.cz, axboe@kernel.dk, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] writeback: fix -Wstringop-truncation warnings Message-ID: <20190730172248.GL28829@quack2.suse.cz> References: <1564075099-27750-1-git-send-email-cai@lca.pw> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1564075099-27750-1-git-send-email-cai@lca.pw> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 25-07-19 13:18:19, Qian Cai wrote: > There are many of those warnings. > > In file included from ./arch/powerpc/include/asm/paca.h:15, > from ./arch/powerpc/include/asm/current.h:13, > from ./include/linux/thread_info.h:21, > from ./include/asm-generic/preempt.h:5, > from ./arch/powerpc/include/generated/asm/preempt.h:1, > from ./include/linux/preempt.h:78, > from ./include/linux/spinlock.h:51, > from fs/fs-writeback.c:19: > In function 'strncpy', > inlined from 'perf_trace_writeback_page_template' at > ./include/trace/events/writeback.h:56:1: > ./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified > bound 32 equals destination size [-Wstringop-truncation] > return __builtin_strncpy(p, q, size); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > Fix it by using the new strscpy_pad() which was introduced in the > commit 458a3bf82df4 ("lib/string: Add strscpy_pad() function") and will > always be NUL-terminated instead of strncpy(). Also, changes strlcpy() > to use strscpy_pad() in this file for consistency. > > Fixes: 455b2864686d ("writeback: Initial tracing support") > Fixes: 028c2dd184c0 ("writeback: Add tracing to balance_dirty_pages") > Fixes: e84d0a4f8e39 ("writeback: trace event writeback_queue_io") > Fixes: b48c104d2211 ("writeback: trace event bdi_dirty_ratelimit") > Fixes: cc1676d917f3 ("writeback: Move requeueing when I_SYNC set to writeback_sb_inodes()") > Fixes: 9fb0a7da0c52 ("writeback: add more tracepoints") > Signed-off-by: Qian Cai Looks good to me. You can add: Reviewed-by: Jan Kara Honza > --- > > v3: Rearrange a long-line a bit to make the code more readable. > v2: Use strscpy_pad() to address the possible data leaking concern from Steve [1]. > Replace strlcpy() as well for consistency. > > [1] https://lore.kernel.org/lkml/20190716170339.1c44719d@gandalf.local.home/ > > include/trace/events/writeback.h | 38 ++++++++++++++++++++------------------ > 1 file changed, 20 insertions(+), 18 deletions(-) > > diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h > index aa7f3aeac740..79095434c1be 100644 > --- a/include/trace/events/writeback.h > +++ b/include/trace/events/writeback.h > @@ -66,8 +66,9 @@ > ), > > TP_fast_assign( > - strncpy(__entry->name, > - mapping ? dev_name(inode_to_bdi(mapping->host)->dev) : "(unknown)", 32); > + strscpy_pad(__entry->name, > + mapping ? dev_name(inode_to_bdi(mapping->host)->dev) : "(unknown)", > + 32); > __entry->ino = mapping ? mapping->host->i_ino : 0; > __entry->index = page->index; > ), > @@ -110,8 +111,8 @@ > struct backing_dev_info *bdi = inode_to_bdi(inode); > > /* may be called for files on pseudo FSes w/ unregistered bdi */ > - strncpy(__entry->name, > - bdi->dev ? dev_name(bdi->dev) : "(unknown)", 32); > + strscpy_pad(__entry->name, > + bdi->dev ? dev_name(bdi->dev) : "(unknown)", 32); > __entry->ino = inode->i_ino; > __entry->state = inode->i_state; > __entry->flags = flags; > @@ -190,8 +191,8 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w > ), > > TP_fast_assign( > - strncpy(__entry->name, > - dev_name(inode_to_bdi(inode)->dev), 32); > + strscpy_pad(__entry->name, > + dev_name(inode_to_bdi(inode)->dev), 32); > __entry->ino = inode->i_ino; > __entry->sync_mode = wbc->sync_mode; > __entry->cgroup_ino = __trace_wbc_assign_cgroup(wbc); > @@ -234,8 +235,9 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w > __field(unsigned int, cgroup_ino) > ), > TP_fast_assign( > - strncpy(__entry->name, > - wb->bdi->dev ? dev_name(wb->bdi->dev) : "(unknown)", 32); > + strscpy_pad(__entry->name, > + wb->bdi->dev ? dev_name(wb->bdi->dev) : > + "(unknown)", 32); > __entry->nr_pages = work->nr_pages; > __entry->sb_dev = work->sb ? work->sb->s_dev : 0; > __entry->sync_mode = work->sync_mode; > @@ -288,7 +290,7 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w > __field(unsigned int, cgroup_ino) > ), > TP_fast_assign( > - strncpy(__entry->name, dev_name(wb->bdi->dev), 32); > + strscpy_pad(__entry->name, dev_name(wb->bdi->dev), 32); > __entry->cgroup_ino = __trace_wb_assign_cgroup(wb); > ), > TP_printk("bdi %s: cgroup_ino=%u", > @@ -310,7 +312,7 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w > __array(char, name, 32) > ), > TP_fast_assign( > - strncpy(__entry->name, dev_name(bdi->dev), 32); > + strscpy_pad(__entry->name, dev_name(bdi->dev), 32); > ), > TP_printk("bdi %s", > __entry->name > @@ -335,7 +337,7 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w > ), > > TP_fast_assign( > - strncpy(__entry->name, dev_name(bdi->dev), 32); > + strscpy_pad(__entry->name, dev_name(bdi->dev), 32); > __entry->nr_to_write = wbc->nr_to_write; > __entry->pages_skipped = wbc->pages_skipped; > __entry->sync_mode = wbc->sync_mode; > @@ -386,7 +388,7 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w > ), > TP_fast_assign( > unsigned long *older_than_this = work->older_than_this; > - strncpy(__entry->name, dev_name(wb->bdi->dev), 32); > + strscpy_pad(__entry->name, dev_name(wb->bdi->dev), 32); > __entry->older = older_than_this ? *older_than_this : 0; > __entry->age = older_than_this ? > (jiffies - *older_than_this) * 1000 / HZ : -1; > @@ -472,7 +474,7 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w > ), > > TP_fast_assign( > - strlcpy(__entry->bdi, dev_name(wb->bdi->dev), 32); > + strscpy_pad(__entry->bdi, dev_name(wb->bdi->dev), 32); > __entry->write_bw = KBps(wb->write_bandwidth); > __entry->avg_write_bw = KBps(wb->avg_write_bandwidth); > __entry->dirty_rate = KBps(dirty_rate); > @@ -537,7 +539,7 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w > > TP_fast_assign( > unsigned long freerun = (thresh + bg_thresh) / 2; > - strlcpy(__entry->bdi, dev_name(wb->bdi->dev), 32); > + strscpy_pad(__entry->bdi, dev_name(wb->bdi->dev), 32); > > __entry->limit = global_wb_domain.dirty_limit; > __entry->setpoint = (global_wb_domain.dirty_limit + > @@ -597,8 +599,8 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w > ), > > TP_fast_assign( > - strncpy(__entry->name, > - dev_name(inode_to_bdi(inode)->dev), 32); > + strscpy_pad(__entry->name, > + dev_name(inode_to_bdi(inode)->dev), 32); > __entry->ino = inode->i_ino; > __entry->state = inode->i_state; > __entry->dirtied_when = inode->dirtied_when; > @@ -671,8 +673,8 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w > ), > > TP_fast_assign( > - strncpy(__entry->name, > - dev_name(inode_to_bdi(inode)->dev), 32); > + strscpy_pad(__entry->name, > + dev_name(inode_to_bdi(inode)->dev), 32); > __entry->ino = inode->i_ino; > __entry->state = inode->i_state; > __entry->dirtied_when = inode->dirtied_when; > -- > 1.8.3.1 > -- Jan Kara SUSE Labs, CR