linux-kernel - [PATCH v2] block: Use div64_ul instead of do

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20211118034033.163550-1-deng.changcheng@zte.com.cn>
Date:   Thu, 18 Nov 2021 03:40:33 +0000
From:   cgel.zte@...il.com
To:     tj@...nel.org
Cc:     axboe@...nel.dk, cgroups@...r.kernel.org,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        zealci@....com.cn, cgel.zte@...il.com, deng.changcheng@....com.cn
Subject: [PATCH v2] block: Use div64_ul instead of do_div

From: Changcheng Deng <deng.changcheng@....com.cn>

do_div() does a 64-by-32 division. Here the divisor is an unsigned long
which on some platforms is 64 bit wide. So use div64_ul instead of do_div
to avoid a possible truncation.

Reported-by: Zeal Robot <zealci@....com.cn>
Signed-off-by: Changcheng Deng <deng.changcheng@....com.cn>
---
 block/blk-throttle.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 39bb6e68a9a2..2db635d66617 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1903,7 +1903,7 @@ static void throtl_downgrade_check(struct throtl_grp *tg)
 
 	if (tg->bps[READ][LIMIT_LOW]) {
 		bps = tg->last_bytes_disp[READ] * HZ;
-		do_div(bps, elapsed_time);
+		bps = div64_ul(bps, elapsed_time);
 		if (bps >= tg->bps[READ][LIMIT_LOW])
 			tg->last_low_overflow_time[READ] = now;
 	}
-- 
2.25.1