Re: [PATCH v2] md : Replace snprintf with scnprintf

[Song Liu <song@kernel.org>]

On Mon, Sep 19, 2022 at 9:47 AM Saurabh Singh Sengar
<ssengar@microsoft.com> wrote:
>
> Is this queued  for 6.0 ?

This is queued for 6.1.

Thanks,
Song

>
> > -----Original Message-----
> > From: Saurabh Sengar <ssengar@linux.microsoft.com>
> > Sent: Wednesday, August 24, 2022 12:21 AM
> > To: song@kernel.org; shli@fb.com; neilb@suse.com; linux-
> > raid@vger.kernel.org; linux-kernel@vger.kernel.org; Saurabh Singh Sengar
> > <ssengar@microsoft.com>; Michael Kelley (LINUX)
> > <mikelley@microsoft.com>; guoqing.jiang@linux.dev
> > Subject: [PATCH v2] md : Replace snprintf with scnprintf
> >
> > 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@microsoft.com>
> > Acked-by: Guoqing Jiang <guoqing.jiang@linux.dev>
> > Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
> > ---
> > V2 :
> >       - Rebase
> >
> >  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 78addfe..857c493
> > 100644
> > --- a/drivers/md/raid0.c
> > +++ b/drivers/md/raid0.c
> > @@ -47,7 +47,7 @@ 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%pg", k?"/":"",
> > +                     len += scnprintf(line+len, 200-len, "%s%pg", k?"/":"",
> >                               conf->devlist[j * raid_disks + k]->bdev);
> >               pr_debug("md: zone%d=[%s]\n", j, line);
> >
> > --
> > 1.8.3.1
>