[PATCH] vsprintf.c cleanups

[PATCH] vsprintf.c cleanups

[Brian Gerst]

[-- Attachment #1: Type: text/plain, Size: 207 bytes --]

- Make sprintf call vsnprintf directly
- use INT_MAX for sprintf and vsprintf

Signed-off-by: Brian Gerst <bgerst@didntduck.org>

  vsprintf.c |    4 ++--
  1 files changed, 2 insertions(+), 2 deletions(-)


[-- Attachment #2: vsprintf.diff --]
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diff -urN linux-2.6.11-rc5/lib/vsprintf.c linux/lib/vsprintf.c
--- linux-2.6.11-rc5/lib/vsprintf.c	2004-08-24 08:43:15.000000000 -0400
+++ linux/lib/vsprintf.c	2005-02-24 17:59:28.000000000 -0500
@@ -580,7 +580,7 @@
  */
 int vsprintf(char *buf, const char *fmt, va_list args)
 {
-	return vsnprintf(buf, (~0U)>>1, fmt, args);
+	return vsnprintf(buf, INT_MAX, fmt, args);
 }
 
 EXPORT_SYMBOL(vsprintf);
@@ -601,7 +601,7 @@
 	int i;
 
 	va_start(args, fmt);
-	i=vsprintf(buf,fmt,args);
+	i=vsnprintf(buf, INT_MAX, fmt, args);
 	va_end(args);
 	return i;
 }

Re: [PATCH] vsprintf.c cleanups

[Horst von Brand]

Brian Gerst <bgerst@didntduck.org> said:
> - Make sprintf call vsnprintf directly
> - use INT_MAX for sprintf and vsprintf

This is the size limit on what is written. 4GiB sounds a bit extreme...
-- 
Dr. Horst H. von Brand                   User #22616 counter.li.org
Departamento de Informatica                     Fono: +56 32 654431
Universidad Tecnica Federico Santa Maria              +56 32 654239
Casilla 110-V, Valparaiso, Chile                Fax:  +56 32 797513

Re: [PATCH] vsprintf.c cleanups

[Brian Gerst]

Horst von Brand wrote:
> Brian Gerst <bgerst@didntduck.org> said:
> 
>>- Make sprintf call vsnprintf directly
>>- use INT_MAX for sprintf and vsprintf
> 
> 
> This is the size limit on what is written. 4GiB sounds a bit extreme...

Sprintf has no limit, which is why it's generally bad to use it.  I just 
replaced an open coded ((~0U)>>1) value with the equivalent INT_MAX.

--
				Brian Gerst

Re: [PATCH] vsprintf.c cleanups

[Arjan van de Ven]

On Fri, 2005-02-25 at 07:28 -0500, Brian Gerst wrote:
> Horst von Brand wrote:
> > Brian Gerst <bgerst@didntduck.org> said:
> > 
> >>- Make sprintf call vsnprintf directly
> >>- use INT_MAX for sprintf and vsprintf
> > 
> > 
> > This is the size limit on what is written. 4GiB sounds a bit extreme...
> 
> Sprintf has no limit, which is why it's generally bad to use it.  I just 
> replaced an open coded ((~0U)>>1) value with the equivalent INT_MAX.

I can see the point of using PAGE_SIZE instead; and if someone really
wants more than that, he/she should use snprintf with a specified
size....

Re: [PATCH] vsprintf.c cleanups

[Horst von Brand]

Brian Gerst <bgerst@didntduck.org> said:
> Horst von Brand wrote:
> > Brian Gerst <bgerst@didntduck.org> said:
> > 
> >>- Make sprintf call vsnprintf directly
> >>- use INT_MAX for sprintf and vsprintf

> > This is the size limit on what is written. 4GiB sounds a bit extreme...

> Sprintf has no limit, which is why it's generally bad to use it.  I just 
> replaced an open coded ((~0U)>>1) value with the equivalent INT_MAX.

Which is the same as "no limit" in my book. Either you know a limit (in
which case vsprintf() is OK) or you don't (in which case vsnprintf() is
just obfuscation).
-- 
Dr. Horst H. von Brand                   User #22616 counter.li.org
Departamento de Informatica                     Fono: +56 32 654431
Universidad Tecnica Federico Santa Maria              +56 32 654239
Casilla 110-V, Valparaiso, Chile                Fax:  +56 32 797513

Re: [PATCH] vsprintf.c cleanups

[Geert Uytterhoeven]

On Fri, 25 Feb 2005, Horst von Brand wrote:
> Brian Gerst <bgerst@didntduck.org> said:
> > Horst von Brand wrote:
> > > Brian Gerst <bgerst@didntduck.org> said:
> > > 
> > >>- Make sprintf call vsnprintf directly
> > >>- use INT_MAX for sprintf and vsprintf
> 
> > > This is the size limit on what is written. 4GiB sounds a bit extreme...
> 
> > Sprintf has no limit, which is why it's generally bad to use it.  I just 
> > replaced an open coded ((~0U)>>1) value with the equivalent INT_MAX.
> 
> Which is the same as "no limit" in my book. Either you know a limit (in
> which case vsprintf() is OK) or you don't (in which case vsnprintf() is
> just obfuscation).

Indeed. So the only place that is allowed to pass the `no limit' value to
snprintf() is in the sprintf() wrapper that calls snprintf().

Calls to sprintf() must not be converted to snprintf(..., `no limit', ...), so
it's easier to find them when doing buffer overflow audits.

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds