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Message-ID: <1287704752.11051.79.camel@Dan>
Date: Thu, 21 Oct 2010 19:45:52 -0400
From: Dan Rosenberg <drosenberg@...curity.com>
To: jon.maloy@...csson.com, allan.stephens@...driver.com
Cc: security@...nel.org, netdev@...r.kernel.org
Subject: TIPC security issues
The tipc_msg_build() function in net/tipc/msg.c is written in such a way
as to create a highly exploitable kernel heap overflow that would allow
a local user to escalate privileges to root by issuing maliciously
crafted sendmsg() calls. At a minimum, the following issues should be
fixed:
1. The tipc_msg_calc_data_size() function is almost totally broken. It
sums together size_t values (iov_lens), but returns an integer. Two
things can go wrong - the total value can wrap around, or on 64-bit
platforms, iov_len values greater than UINT_MAX will be truncated.
2. The comparison of dsz to TIPC_MAX_USER_MSG_SIZE is signed, so
negative (large unsigned) values will pass this check.
3. The comparison of sz to max_size is also signed.
As a result of these issues, it's possible to cause the allocation of a
small heap buffer and the subsequent copying of a carefully controlled
larger amount of data into that buffer.
I haven't found a Linux distribution that defines a module alias for
TIPC (even though most compile it as a module), so an administrator will
have had to explicitly load the TIPC module for a system to be
vulnerable.
-Dan
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