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[gentoo-security] GLSA: pptpd (200304-08)
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Joined: 16 Apr 2002
Posts: 16147
Location: Colorado

PostPosted: Mon Apr 28, 2003 1:31 pm    Post subject: [gentoo-security] GLSA: pptpd (200304-08) Reply with quote

Daniel Ahlberg wrote:
- - - ---------------------------------------------------------------------
- - - ---------------------------------------------------------------------

PACKAGE : pptpd
SUMMARY : buffer overflow
DATE : 2003-04-28 09:22 UTC
EXPLOIT : remote
FIXED VERSION : >=pptpd-
CVE : CAN-2003-0213

- - - ---------------------------------------------------------------------

- - From advisory:

"PPTP packet header contain 16bit length which specifies the full size of
the packet:

bytes_this = read(clientFd, packet + bytes_ttl, 2 - bytes_ttl);
// ...
bytes_ttl += bytes_this;
// ...
length = htons(*(u_int16_t *) packet);
if (length > PPTP_MAX_CTRL_PCKT_SIZE) {
// abort

Looks good so far, except:

bytes_this = read(clientFd, packet + bytes_ttl, length - bytes_ttl);

If given length was 0 or 1, the "length - bytes_ttl" result is -1 or -2,
which means that it reads unlimited amount of data from client into
"packet", which is a buffer located in stack.

The exploitability only depends on if libc allows the size parameter to be
larger than SSIZE_MAX bytes. GLIBC does, Solaris and *BSD don't."

Read the full advisory at:


It is recommended that all Gentoo Linux users who are running
net-dialup/pptpd upgrade to pptpd- as follows:

emerge sync
emerge pptpd
emerge clean

- - - --------------------------------------------------------------------- - GnuPG key is available at
- - - ---------------------------------------------------------------------

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