Messages in this thread | | | Date | Wed, 11 Mar 2020 08:24:51 +0100 | From | Takashi Iwai <> | Subject | Re: [PATCH] drivers/base/cpu: Use scnprintf() for avoiding potential buffer overflow |
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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
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