Re: [PATCH] sysfs.txt: update show method notes about sprintf/snprintf/scnprintf usage

[Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>]

Cc Jonathan and linux-doc

On (06/24/15 23:03), Greg KH <gregkh@linuxfoundation.org> (gregkh@linuxfoundation.org) wrote:
[..]
> > > -- show() should always use scnprintf().
> > > +- show() must not use snprintf() when formatting a value to be
> > > +  returned to user space. For small single values you can use
> > > +  sprintf() otherwise you must use scnprintf().
> > 
> > Well, a single value can easily overflow
> > 
> > 	sprintf(buf, "%s", dev->large_value);
> 
> That's an obviously foolish sysfs attribute, if you do that, you deserve
> the kernel crash :)

:)

And the 'always use scnprintf()' rule keeps all of us on the safe
side (almost for free).

> > Probably the wording better be "if you guarantee that overflow will
> > never happen, then you can use ...".
> 
> For a document that no one has obviously read in the past 5 years, I
> really doubt we need to work too hard on the exact specific wording of
> it.

Oh, it's especially pleasant and satisfactory to ignore
a well-written and scrupulous documentation  :)  just kidding.

	-ss