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Source: http://pastebin.com/HBWiH92j

PSN-2011-08-327
View Bulletin PSN-2011-08-327
Title MX Series MPC crash in Ktree::createFourWayNode after BGP UPDATE
Products Affected This issue can affect any MX Series router with port
concentrators based on the Trio chipset -- such as the MPC or embedded into
the MX80 -- with active protocol-based route prefix additions/deletions
occurring.
Platforms Affected
Security
JUNOS 11.x
MX-series
JUNOS 10.x
SIRT Security Advisory
SIRT Security Notice
Revision Number 1
Issue Date 2011-08-08

PSN Issue :
MPCs (Modular Port Concentrators) installed in an MX Series router may
crash upon receipt of very specific and unlikely route prefix
install/delete actions, such as a BGP routing update. The set of route
prefix updates is non-deterministic and exceedingly unlikely to occur.
Junos versions affected include 10.0, 10.1, 10.2, 10.3, 10.4 prior to
10.4R6, and 11.1 prior to 11.1R4. The trigger for the MPC crash was
determined to be a valid BGP UPDATE received from a registered network
service provider, although this one UPDATE was determined to not be solely
responsible for the crashes. A complex sequence of preconditions is
required to trigger this crash. Both IPv4 and IPv6 routing prefix updates
can trigger this MPC crash.

There is no indication that this issue was triggered maliciously. Given the
complexity of conditions required to trigger this issue, the probability of
exploiting this defect is extremely low.

The assertions (crash) all occurred in the code used to store routing
information, called Ktree, on the MPC. Due to the order and mix of adds and
deletes to the tree, certain combinations of address adds and deletes can
corrupt the data structures within the MPC, which in turn can cause this
line card crash. The MPC recovers and returns to service quickly, and
without operator intervention.

This issue only affects MX Series routers with port concentrators based on
the Trio chipset, such as the MPC or embedded into the MX80. No other
product or platform is vulnerable to this issue.
Solution:
The Ktree code has been updated and enhanced to ensure that combinations
and permutations of routing updates will not corrupt the state of the line
card. Extensive testing has been performed to validate an exceedingly large
combination and permutation of route prefix additions and deletions.

All Junos OS software releases built on or after 2011-08-03 have fixed this
specific issue. Releases containing the fix specifically include: 10.0S18,
10.4R6, 11.1R4, 11.2R1, and all subsequent releases (i.e. all releases
built after 11.2R1).

This issue is being tracked as PR 610864. While this PR may not be viewable
by customers, it can be used as a reference when discussing the issue with
JTAC.

KB16765 - "In which releases are vulnerabilities fixed?" describes which
release vulnerabilities are fixed as per our End of Engineering and End of
Life support policies.

Workarounds
No known workaround exists for this issue.

Thanks to those who replied off-list,

Ben
On 7 November 2011 18:00, Ben Ward <[email protected]> wrote:

> Hi All,
>
> Does anyone have any further information to what was discussed in this
> thread?
>
> http://mailman.nanog.org/pipermail/nanog/2011-November/041653.html
> From what I can gather there and on Twitter there was a bug which caused
> Junipers to core dump and either flap all interfaces or reload the BGP
> process.
>
> Can anyone shed any light on this?
>
> Ben
>
> --
> [email protected] | http://crouchingbadger.com
>



-- 
[email protected] | http://crouchingbadger.com


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