[PATCH 5.4 252/255] md: Replace snprintf with scnprintf
From: Greg Kroah-Hartman
Date: Mon Oct 24 2022 - 09:11:01 EST
From: Saurabh Sengar <ssengar@xxxxxxxxxxxxxxxxxxx>
commit 1727fd5015d8f93474148f94e34cda5aa6ad4a43 upstream.
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
Fixes: 766038846e875 ("md/raid0: replace printk() with pr_*()")
Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
Acked-by: Guoqing Jiang <guoqing.jiang@xxxxxxxxx>
Signed-off-by: Saurabh Sengar <ssengar@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Song Liu <song@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/raid0.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -63,8 +63,8 @@ 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?"/":"",
- bdevname(conf->devlist[j*raid_disks
+ 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);