* [PATCH] drivers/base/cpu: Use scnprintf() for avoiding potential buffer overflow
@ 2020-03-11 7:12 Takashi Iwai
2020-03-11 7:19 ` Greg Kroah-Hartman
0 siblings, 1 reply; 3+ messages in thread
From: Takashi Iwai @ 2020-03-11 7:12 UTC (permalink / raw)
To: Greg Kroah-Hartman; +Cc: Rafael J . Wysocki, linux-kernel
Since snprintf() returns the would-be-output size instead of the
actual output size, the succeeding calls may go beyond the given
buffer limit. Fix it by replacing with scnprintf().
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
drivers/base/cpu.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 6265871a4af2..0abcd9d68714 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -231,7 +231,7 @@ static struct cpu_attr cpu_attrs[] = {
static ssize_t print_cpus_kernel_max(struct device *dev,
struct device_attribute *attr, char *buf)
{
- int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
+ int n = scnprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
return n;
}
static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
@@ -258,13 +258,13 @@ static ssize_t print_cpus_offline(struct device *dev,
buf[n++] = ',';
if (nr_cpu_ids == total_cpus-1)
- n += snprintf(&buf[n], len - n, "%u", nr_cpu_ids);
+ n += scnprintf(&buf[n], len - n, "%u", nr_cpu_ids);
else
- n += snprintf(&buf[n], len - n, "%u-%d",
+ n += scnprintf(&buf[n], len - n, "%u-%d",
nr_cpu_ids, total_cpus-1);
}
- n += snprintf(&buf[n], len - n, "\n");
+ n += scnprintf(&buf[n], len - n, "\n");
return n;
}
static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
--
2.16.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] drivers/base/cpu: Use scnprintf() for avoiding potential buffer overflow
2020-03-11 7:12 [PATCH] drivers/base/cpu: Use scnprintf() for avoiding potential buffer overflow Takashi Iwai
@ 2020-03-11 7:19 ` Greg Kroah-Hartman
2020-03-11 7:24 ` Takashi Iwai
0 siblings, 1 reply; 3+ messages in thread
From: Greg Kroah-Hartman @ 2020-03-11 7:19 UTC (permalink / raw)
To: Takashi Iwai; +Cc: Rafael J . Wysocki, linux-kernel
On Wed, Mar 11, 2020 at 08:12:00AM +0100, Takashi Iwai wrote:
> Since snprintf() returns the would-be-output size instead of the
> actual output size, the succeeding calls may go beyond the given
> buffer limit. Fix it by replacing with scnprintf().
>
> Signed-off-by: Takashi Iwai <tiwai@suse.de>
> ---
> drivers/base/cpu.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
> index 6265871a4af2..0abcd9d68714 100644
> --- a/drivers/base/cpu.c
> +++ b/drivers/base/cpu.c
> @@ -231,7 +231,7 @@ static struct cpu_attr cpu_attrs[] = {
> static ssize_t print_cpus_kernel_max(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> - int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
> + int n = scnprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
This should just be "sprintf()" as we "know" that fitting a single
number will work.
> return n;
> }
> static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
> @@ -258,13 +258,13 @@ static ssize_t print_cpus_offline(struct device *dev,
> buf[n++] = ',';
>
> if (nr_cpu_ids == total_cpus-1)
> - n += snprintf(&buf[n], len - n, "%u", nr_cpu_ids);
> + n += scnprintf(&buf[n], len - n, "%u", nr_cpu_ids);
> else
> - n += snprintf(&buf[n], len - n, "%u-%d",
> + n += scnprintf(&buf[n], len - n, "%u-%d",
> nr_cpu_ids, total_cpus-1);
> }
>
> - n += snprintf(&buf[n], len - n, "\n");
> + n += scnprintf(&buf[n], len - n, "\n");
this part looks sane, can you respin this?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] drivers/base/cpu: Use scnprintf() for avoiding potential buffer overflow
2020-03-11 7:19 ` Greg Kroah-Hartman
@ 2020-03-11 7:24 ` Takashi Iwai
0 siblings, 0 replies; 3+ messages in thread
From: Takashi Iwai @ 2020-03-11 7:24 UTC (permalink / raw)
To: Greg Kroah-Hartman; +Cc: Rafael J . Wysocki, linux-kernel
On Wed, 11 Mar 2020 08:19:35 +0100,
Greg Kroah-Hartman wrote:
>
> On Wed, Mar 11, 2020 at 08:12:00AM +0100, Takashi Iwai wrote:
> > Since snprintf() returns the would-be-output size instead of the
> > actual output size, the succeeding calls may go beyond the given
> > buffer limit. Fix it by replacing with scnprintf().
> >
> > Signed-off-by: Takashi Iwai <tiwai@suse.de>
> > ---
> > drivers/base/cpu.c | 8 ++++----
> > 1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
> > index 6265871a4af2..0abcd9d68714 100644
> > --- a/drivers/base/cpu.c
> > +++ b/drivers/base/cpu.c
> > @@ -231,7 +231,7 @@ static struct cpu_attr cpu_attrs[] = {
> > static ssize_t print_cpus_kernel_max(struct device *dev,
> > struct device_attribute *attr, char *buf)
> > {
> > - int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
> > + int n = scnprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
>
> This should just be "sprintf()" as we "know" that fitting a single
> number will work.
>
> > return n;
> > }
> > static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
> > @@ -258,13 +258,13 @@ static ssize_t print_cpus_offline(struct device *dev,
> > buf[n++] = ',';
> >
> > if (nr_cpu_ids == total_cpus-1)
> > - n += snprintf(&buf[n], len - n, "%u", nr_cpu_ids);
> > + n += scnprintf(&buf[n], len - n, "%u", nr_cpu_ids);
> > else
> > - n += snprintf(&buf[n], len - n, "%u-%d",
> > + n += scnprintf(&buf[n], len - n, "%u-%d",
> > nr_cpu_ids, total_cpus-1);
> > }
> >
> > - n += snprintf(&buf[n], len - n, "\n");
> > + n += scnprintf(&buf[n], len - n, "\n");
>
> this part looks sane, can you respin this?
OK, will do it.
Thanks for a quick review!
Takashi
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-03-11 7:12 [PATCH] drivers/base/cpu: Use scnprintf() for avoiding potential buffer overflow Takashi Iwai
2020-03-11 7:19 ` Greg Kroah-Hartman
2020-03-11 7:24 ` Takashi Iwai
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