Date: Thu, 19 Jul 2001 20:59:48 +0300 From: Ruslan Ermilov <ru@FreeBSD.ORG> To: Matt Dillon <dillon@earth.backplane.com> Cc: security@FreeBSD.ORG Subject: Re: [PATCH] Re: FreeBSD remote root exploit ? Message-ID: <20010719205948.D67829@sunbay.com> In-Reply-To: <200107191752.f6JHqer75736@earth.backplane.com>; from dillon@earth.backplane.com on Thu, Jul 19, 2001 at 10:52:40AM -0700 References: <5.1.0.14.0.20010719001357.03e22638@192.168.0.12> <014d01c11031$bdab5a10$2001a8c0@clitoris> <20010719201407.B61061@sunbay.com> <003701c11077$b3125400$0d00a8c0@alexus> <3B5718A0.2B650C9C@oksala.org> <200107191752.f6JHqer75736@earth.backplane.com>
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On Thu, Jul 19, 2001 at 10:52:40AM -0700, Matt Dillon wrote:
>
> :go to /usr/src/crypto/telnet/telnetd
> :and type
> :shell~# patch -p < /where/is/the/file.patch
>
> It isn't really safe code. If the data being formatted is large
> r then the format argument you can overflow the buffer, and the
> 'ret' from vsnprintf() is the amount of data that would have been
> output if the buffer had been large enough, not the amount of data
> that was actually output. Also, size_t is unsigned, which means
> if you overflow the buffer by one byte you are screwed.
>
> There appear to be a number of places (mainly the DIAG code, but also
> the ENCRYPT code) where this is true. This patch will fix the existing
> options-based hole, but doesn't close it.
>
Doesn't this handle this?
int
output_data(const char *format, ...)
{
va_list args;
size_t remaining, ret;
va_start(args, format);
remaining = BUFSIZ - (nfrontp - netobuf);
/* try a netflush() if the room is too low */
if (strlen(format) > remaining || BUFSIZ / 4 > remaining) {
^^^^^^^^^^^^^^^^^^^^^^^^^^
netflush();
remaining = BUFSIZ - (nfrontp - netobuf);
}
ret = vsnprintf(nfrontp, remaining, format, args);
nfrontp += ret;
va_end(args);
return ret;
}
--
Ruslan Ermilov Oracle Developer/DBA,
ru@sunbay.com Sunbay Software AG,
ru@FreeBSD.org FreeBSD committer,
+380.652.512.251 Simferopol, Ukraine
http://www.FreeBSD.org The Power To Serve
http://www.oracle.com Enabling The Information Age
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