2010-08-11 13:44:17

by Davidlohr Bueso

Subject: [PATCH] kernel/ksysfs: use snprintf for sysfs show

Use snprintf(buf, PAGE_SIZE, ...) instead of sprintf for sysfs show
methods. This is suggested in Documentation/filesystems/sysfs.txt

Signed-off-by: Davidlohr Bueso <[email protected]>
---
kernel/ksysfs.c | 20 +++++++++++---------
1 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index 0b624e7..d7cef25 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -29,7 +29,9 @@ static struct kobj_attribute _name##_attr = \
static ssize_t uevent_seqnum_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
- return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum);
+ return snprintf(buf, PAGE_SIZE, "%llu\n",
+ (unsigned long long)uevent_seqnum);
+
}
KERNEL_ATTR_RO(uevent_seqnum);

@@ -37,7 +39,7 @@ KERNEL_ATTR_RO(uevent_seqnum);
static ssize_t uevent_helper_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
- return sprintf(buf, "%s\n", uevent_helper);
+ return snprintf(buf, PAGE_SIZE, "%s\n", uevent_helper);
}
static ssize_t uevent_helper_store(struct kobject *kobj,
struct kobj_attribute *attr,
@@ -58,7 +60,7 @@ KERNEL_ATTR_RW(uevent_helper);
static ssize_t profiling_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
- return sprintf(buf, "%d\n", prof_on);
+ return snprintf(buf, PAGE_SIZE, "%d\n", prof_on);
}
static ssize_t profiling_store(struct kobject *kobj,
struct kobj_attribute *attr,
@@ -89,21 +91,21 @@ KERNEL_ATTR_RW(profiling);
static ssize_t kexec_loaded_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
- return sprintf(buf, "%d\n", !!kexec_image);
+ return snprintf(buf, PAGE_SIZE, "%d\n", !!kexec_image);
}
KERNEL_ATTR_RO(kexec_loaded);

static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
- return sprintf(buf, "%d\n", !!kexec_crash_image);
+ return snprintf(buf, PAGE_SIZE, "%d\n", !!kexec_crash_image);
}
KERNEL_ATTR_RO(kexec_crash_loaded);

static ssize_t kexec_crash_size_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
- return sprintf(buf, "%zu\n", crash_get_memory_size());
+ return snprintf(buf, PAGE_SIZE, "%zu\n", crash_get_memory_size());
}
static ssize_t kexec_crash_size_store(struct kobject *kobj,
struct kobj_attribute *attr,
@@ -123,9 +125,9 @@ KERNEL_ATTR_RW(kexec_crash_size);
static ssize_t vmcoreinfo_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
- return sprintf(buf, "%lx %x\n",
- paddr_vmcoreinfo_note(),
- (unsigned int)vmcoreinfo_max_size);
+ return snprintf(buf, PAGE_SIZE, "%lx %x\n",
+ paddr_vmcoreinfo_note(),
+ (unsigned int)vmcoreinfo_max_size);
}
KERNEL_ATTR_RO(vmcoreinfo);

--
1.7.0.4

2010-08-11 14:05:19

by Al Viro

Subject: Re: [PATCH] kernel/ksysfs: use snprintf for sysfs show

On Wed, Aug 11, 2010 at 09:44:10AM -0400, Davidlohr Bueso wrote:
> Use snprintf(buf, PAGE_SIZE, ...) instead of sprintf for sysfs show
> methods. This is suggested in Documentation/filesystems/sysfs.txt

... therefore it must be done, the common sense be damned.

> Signed-off-by: Davidlohr Bueso <[email protected]>
> ---

> static ssize_t uevent_seqnum_show(struct kobject *kobj,
> struct kobj_attribute *attr, char *buf)
> {
> - return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum);
> + return snprintf(buf, PAGE_SIZE, "%llu\n",
> + (unsigned long long)uevent_seqnum);

A-yup - that's an improvement, all right, on them evil boxen that got
long long so huge that its decimal representation won't fit into a page.

NAK. Cargo-cult programming is bad.

2010-08-11 15:31:42

by Greg KH

Subject: Re: [PATCH] kernel/ksysfs: use snprintf for sysfs show

On Wed, Aug 11, 2010 at 09:44:10AM -0400, Davidlohr Bueso wrote:
> Use snprintf(buf, PAGE_SIZE, ...) instead of sprintf for sysfs show
> methods. This is suggested in Documentation/filesystems/sysfs.txt

As Al pointed out, none of these will ever overflow so it makes no sense
to change them.

thanks,

greg k-h