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Date: Tue, 25 Feb 2003 10:41:16 -0600
From: Mark Hatle <fray@...sta.com>
To: xvendor@...ts.openwall.com
Subject: Re: zlib gzprintf() patch
Is this due to an audit? Or did you find a problem/crash w/ errant data?
--Mark
Solar Designer wrote:
> Hi,
>
> Just thought I'd share the tiny patch that went into Owl. Attached.
>
> The lack of configure checking for vsnprintf() is intentional (I want
> this to not compile without a vsnprintf() anyway).
>
> The Owl change log entry is:
>
> 2003/02/25 Package: zlib
> Corrected a potential buffer overflow in gzprintf(), thanks to Bugtraq
> postings by Crazy Einstein, Richard Kettlewell, and Carlo Marcelo
> Arenas Belon.
>
>
>
> ------------------------------------------------------------------------
>
> diff -ur zlib-1.1.4.orig/gzio.c zlib-1.1.4/gzio.c
> --- zlib-1.1.4.orig/gzio.c Mon Mar 11 16:16:01 2002
> +++ zlib-1.1.4/gzio.c Tue Feb 25 07:08:36 2003
> @@ -529,14 +529,9 @@
> int len;
>
> va_start(va, format);
> -#ifdef HAS_vsnprintf
> - (void)vsnprintf(buf, sizeof(buf), format, va);
> -#else
> - (void)vsprintf(buf, format, va);
> -#endif
> + len = vsnprintf(buf, sizeof(buf), format, va);
> va_end(va);
> - len = strlen(buf); /* some *sprintf don't return the nb of bytes written */
> - if (len <= 0) return 0;
> + if (len <= 0 || len >= sizeof(buf)) return 0;
>
> return gzwrite(file, buf, (unsigned)len);
> }
> @@ -552,15 +547,9 @@
> char buf[Z_PRINTF_BUFSIZE];
> int len;
>
> -#ifdef HAS_snprintf
> - snprintf(buf, sizeof(buf), format, a1, a2, a3, a4, a5, a6, a7, a8,
> + len = snprintf(buf, sizeof(buf), format, a1, a2, a3, a4, a5, a6, a7, a8,
> a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
> -#else
> - sprintf(buf, format, a1, a2, a3, a4, a5, a6, a7, a8,
> - a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
> -#endif
> - len = strlen(buf); /* old sprintf doesn't return the nb of bytes written */
> - if (len <= 0) return 0;
> + if (len <= 0 || len >= sizeof(buf)) return 0;
>
> return gzwrite(file, buf, len);
> }
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