From 1727fd5015d8f93474148f94e34cda5aa6ad4a43 Mon Sep 17 00:00:00 2001
From: Saurabh Sengar <ssengar@linux.microsoft.com>
Date: Tue, 23 Aug 2022 11:51:04 -0700
Subject: [PATCH] md: Replace snprintf with scnprintf
Git-commit: 1727fd5015d8f93474148f94e34cda5aa6ad4a43
Patch-mainline: v6.1-rc1
References: git-fixes, bsc#1164051
Current code produces a warning as shown below when total characters
in the constituent block device names plus the slashes exceeds 200.
snprintf() returns the number of characters generated from the given
input, which could cause the expression 200-len to wrap around
to a large positive number. Fix this by using scnprintf() instead,
which returns the actual number of characters written into the buffer.
[ 1513.267938] ------------[ cut here ]------------
[ 1513.267943] WARNING: CPU: 15 PID: 37247 at <snip>/lib/vsprintf.c:2509 vsnprintf+0x2c8/0x510
[ 1513.267944] Modules linked in: <snip>
[ 1513.267969] CPU: 15 PID: 37247 Comm: mdadm Not tainted 5.4.0-1085-azure #90~18.04.1-Ubuntu
[ 1513.267969] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 05/09/2022
[ 1513.267971] RIP: 0010:vsnprintf+0x2c8/0x510
<-snip->
[ 1513.267982] Call Trace:
[ 1513.267986] snprintf+0x45/0x70
[ 1513.267990] ? disk_name+0x71/0xa0
[ 1513.267993] dump_zones+0x114/0x240 [raid0]
[ 1513.267996] ? _cond_resched+0x19/0x40
[ 1513.267998] raid0_run+0x19e/0x270 [raid0]
[ 1513.268000] md_run+0x5e0/0xc50
[ 1513.268003] ? security_capable+0x3f/0x60
[ 1513.268005] do_md_run+0x19/0x110
[ 1513.268006] md_ioctl+0x195e/0x1f90
[ 1513.268007] blkdev_ioctl+0x91f/0x9f0
[ 1513.268010] block_ioctl+0x3d/0x50
[ 1513.268012] do_vfs_ioctl+0xa9/0x640
[ 1513.268014] ? __fput+0x162/0x260
[ 1513.268016] ksys_ioctl+0x75/0x80
[ 1513.268017] __x64_sys_ioctl+0x1a/0x20
[ 1513.268019] do_syscall_64+0x5e/0x200
[ 1513.268021] entry_SYSCALL_64_after_hwframe+0x44/0xa9
(Coly Li: rebased for Linux v4.12 based SUSE kernel)
Fixes: 766038846e875 ("md/raid0: replace printk() with pr_*()")
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Acked-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Coly Li <colyli@suse.de>
---
drivers/md/raid0.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -70,7 +70,7 @@ static void dump_zones(struct mddev *mdd
int len = 0;
for (k = 0; k < conf->strip_zone[j].nb_dev; k++)
- len += snprintf(line+len, 200-len, "%s%s", k?"/":"",
+ len += scnprintf(line+len, 200-len, "%s%s", k?"/":"",
bdevname(conf->devlist[j*raid_disks
+ k]->bdev, b));
pr_debug("md: zone%d=[%s]\n", j, line);