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Date: Tue, 5 Dec 2017 00:11:41 +0000
From: Mohamed Ghannam <simo.ghannam@...il.com>
To: oss-security@...ts.openwall.com
Subject: CVE-2017-8824 linux: use-after-free in DCCP code

Hi,


This is an announcement for CVE-2017-8824 which is a use-after-free
vulnerability

I found in Linux DCCP socket. It can be used to gain kernel code execution
from unprivileged processes.



You’ll find in attachment the proof of concept code and the kernel panic
log.



#######   BUG DETAILS  ############



When a socket sock object is in DCCP_LISTEN  state and connect() system
call is being called with AF_UNSPEC,

the dccp_disconnect() puts sock state into DCCP_CLOSED, and forgets to free
dccps_hc_rx_ccid/dccps_hc_tx_ccid and assigns NULL to them,

then when we call connect() again with AF_INET6 sockaddr family, the sock
object gets cloned via dccp_create_openreq_child() and returns a new sock
object,

which holds references of dccps_hc_rx_ccid and dccps_hc_tx_ccid of the old
sock object, and this leads to both the old and new sock objects can use
the same memory.



#######   LINKS  ############



http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=2017-8824

http://lists.openwall.net/netdev/2017/12/04/224



#######   CREDITS  ############



Mohamed Ghannam

Content of type "text/html" skipped

Download attachment "kasan_report.log" of type "application/octet-stream" (8589 bytes)

View attachment "poc.c" of type "text/x-csrc" (2459 bytes)

Download attachment "rip.log" of type "application/octet-stream" (2861 bytes)

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