[PATCH] 2.4 vsnprintf fix.

[PATCH] 2.4 vsnprintf fix.

[Rusty Russell]

Following patch fixes calling vsnprintf with (NULL, 0) to get the
length of the string.  The problem is that the end ptr is set to
0xFFFFFFFF in this case, causing a write into address 0 as start <
end.

Cheers,
Rusty. 
--
Premature optmztion is rt of all evl. --DK

--- working-pmac-module/lib/vsprintf.c.~1~	Mon Sep 17 08:53:56 2001
+++ working-pmac-module/lib/vsprintf.c	Thu Sep 20 21:26:05 2001
@@ -246,6 +246,8 @@
 				/* 'z' support added 23/7/1999 S.H.    */
 				/* 'z' changed to 'Z' --davidm 1/25/99 */
 
+	/* buf = NULL, size = 0 is common for getting length */
+	if (size == 0) buf = (void *)1;
 	str = buf;
 	end = buf + size - 1;

Re: [PATCH] 2.4 vsnprintf fix.

[Crutcher Dunnavant]

++ 20/09/01 21:29 +1000 - Rusty Russell:
> Following patch fixes calling vsnprintf with (NULL, 0) to get the
> length of the string.  The problem is that the end ptr is set to
> 0xFFFFFFFF in this case, causing a write into address 0 as start <
> end.

Doh! Egg on face. Between this and the sysrq bugs, I'm thinking of going
into dance instead of hacking anymore. Sorry about this, it is a basic
mistake (right up there with going up against a scicilian when death is
on the line.)

> 
> Cheers,
> Rusty. 
> --
> Premature optmztion is rt of all evl. --DK
> 
> --- working-pmac-module/lib/vsprintf.c.~1~	Mon Sep 17 08:53:56 2001
> +++ working-pmac-module/lib/vsprintf.c	Thu Sep 20 21:26:05 2001
> @@ -246,6 +246,8 @@
>  				/* 'z' support added 23/7/1999 S.H.    */
>  				/* 'z' changed to 'Z' --davidm 1/25/99 */
>  
> +	/* buf = NULL, size = 0 is common for getting length */
> +	if (size == 0) buf = (void *)1;
>  	str = buf;
>  	end = buf + size - 1;
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

-- 
Crutcher        <crutcher@datastacks.com>
GCS d--- s+:>+:- a-- C++++$ UL++++$ L+++$>++++ !E PS+++ PE Y+ PGP+>++++
    R-(+++) !tv(+++) b+(++++) G+ e>++++ h+>++ r* y+>*$