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[PATCH] md : Replace snprintf with scnprintf

Saurabh Sengar posted 1 patch 3 years, 8 months ago
There is a newer version of this series
drivers/md/raid0.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
[PATCH] md : Replace snprintf with scnprintf
Posted by Saurabh Sengar 3 years, 8 months ago 
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_*()")
Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
---
 drivers/md/raid0.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index b21e101..b6f0fc1 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -48,7 +48,7 @@ static void dump_zones(struct mddev *mddev)
 		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);
-- 
1.8.3.1
Re: [PATCH] md : Replace snprintf with scnprintf
Posted by Guoqing Jiang 3 years, 8 months ago 

On 8/5/22 1:25 AM, Saurabh Sengar wrote:
> 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_*()")
> Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
> ---
>   drivers/md/raid0.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
> index b21e101..b6f0fc1 100644
> --- a/drivers/md/raid0.c
> +++ b/drivers/md/raid0.c
> @@ -48,7 +48,7 @@ static void dump_zones(struct mddev *mddev)
>   		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);

Acked-by: Guoqing Jiang <guoqing.jiang@linux.dev>

Thanks,
Guoqing
Re: [PATCH] md : Replace snprintf with scnprintf
Posted by Song Liu 3 years, 7 months ago 
On Thu, Aug 4, 2022 at 6:10 PM Guoqing Jiang <guoqing.jiang@linux.dev> wrote:
>
>
>
> On 8/5/22 1:25 AM, Saurabh Sengar wrote:
> > 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_*()")
> > Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>

The patch doesn't apply. Could you please rebase and resend?

Thanks,
Song

> > ---
> >   drivers/md/raid0.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
> > index b21e101..b6f0fc1 100644
> > --- a/drivers/md/raid0.c
> > +++ b/drivers/md/raid0.c
> > @@ -48,7 +48,7 @@ static void dump_zones(struct mddev *mddev)
> >               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);
>
> Acked-by: Guoqing Jiang <guoqing.jiang@linux.dev>
>
> Thanks,
> Guoqing
RE: [PATCH] md : Replace snprintf with scnprintf
Posted by Michael Kelley (LINUX) 3 years, 8 months ago 
From: Saurabh Sengar <ssengar@linux.microsoft.com> Sent: Thursday, August 4, 2022 10:26 AM
> 
> 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_*()")
> Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
> ---
>  drivers/md/raid0.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
> index b21e101..b6f0fc1 100644
> --- a/drivers/md/raid0.c
> +++ b/drivers/md/raid0.c
> @@ -48,7 +48,7 @@ static void dump_zones(struct mddev *mddev)
>  		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);
> --
> 1.8.3.1

Reviewed-by: Michael Kelley <mikelley@microsoft.com>

Patchew 2.1-devel-ea86937

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