A Security Vulnerability in IPv4 Forwarding may Allow a Remote User to Panic the System

Category
Security

Release Phase
Resolved

Bug Id
6478933

Product
Solaris 10 Operating System
OpenSolaris

Date of Resolved Release
15-Dec-2008

Solaris 10 kernel patches 120011-14 (SPARC) and 120012-14 (x86) introduced a security vulnerability in IPv4 forwarding:

1. Impact

Solaris 10 kernel patches 120011-14 (SPARC) and 120012-14 (x86) introduced a security vulnerability in IPv4 forwarding which may allow a remote unprivileged user to panic the system. This is a type of Denial of Service (DoS).

2. Contributing Factors

This issue can occur in the following releases:

SPARC Platform

Solaris 10 with patch 120011-14 and without patch 138888-01
OpenSolaris based upon builds snv_47 through snv_82

x86 Platform

Solaris 10 with patch 120012-14 and without patch 138889-01
OpenSolaris based upon builds snv_47 through snv_82

Note 1: Solaris 8 and 9 are not impacted by this issue.

Note 2: OpenSolaris distributions may include additional bug fixes above and beyond the build from which it was derived.

To determine the base build of OpenSolaris, the following command can be used:

    $ uname -v
    snv_86

Note 3: A system is only affected by this issue if it is configured to use IPv4, has a network route with a gateway of 127.0.0.1, and the route does not have the blackhole flag set. To determine if a system is configured this way, the following command can be used:

    $ netstat -rnf inet

    Routing Table: IPv4
    Destination           Gateway     Flags   Ref   Use   Interface  
    default              192.168.0.1    UG     1    2254
    12.1.1.1             127.0.0.1      UH     1    454     lo0
    13.0.0.0             127.0.0.1      U      1    112     lo0
    192.168.0.0          192.168.0.5    U      1    1357    bge0
    224.0.0.0            192.168.0.5    U      1    0       bge0
    127.0.0.1            127.0.0.1      UH     3    744     lo0

In the above example, routes 12.1.1.1 and 13.0.0.0 may place the system at risk. Individual routes must then be checked using the "route get" command:

    $ route get 12.1.1.1 | grep "flags:"
         flags: <UP,DONE,STATIC>
    $ route get 13.0.0.0 | grep "flags:"
         flags: <UP,DONE,STATIC,BLACKHOLE>

The route to 12.1.1.1 does not have the BLACKHOLE flag set, and may be affected by this issue.
The route to 13.0.0.0 has the BLACKHOLE flag set, and therefore this route is not affected.

Note 4: This issue affects systems regardless of whether IPv4 forwarding has been configured (either using the ipv4-forwarding option of routeadm(1M) or setting the ip_forwarding kernel tunable with ndd(1M)).

3. Symptoms

If the described issue occurs, the affected system will panic and may produce a crashdump with a panic string and a stack trace similar to the following:

    BAD TRAP: type=31 rp=2a100047250 addr=1d8 mmu_fsr=0 occurred in module
    "ip" due to a NULL pointer dereference

    ire_add+0xdc(2a1008193b0, 0, 0, 0, 1, 600008338c8)
    ire_forward+0x524(20, 60000833890, 60000833980, 60000086388,
    6000012d848, 30006c36000)
    ip_fast_forward+0xd8(e0000000, d010101, 600002af428, 60000936ae0, 0, 1)
    ip_input+0x5a0(600012826e0, 3000851e040, 0, 600002af428, 0, 0)
    i_dls_link_rx+0x1f0(60000333d20, 3000851e040, 0, 60000936ae0,
    2a100819710, 2a100819718)
    mac_rx+0x50(60000331e08, 3000851e040, 60000936ae0, 12f8100, 0,
    600002f83d0)
    bge_receive+0x408(46, 3000818e000, 60000936ae0, 60000936ae0,
    ffffffffffffffff, 2f5c)
    bge_intr+0x188(3000818e000, 10000001f, 0, 2c00, 30008190de0, 0)
    pci_intr_wrapper+0xb4(30004f8e668, 6000030df10, 0, 0, 0, 600002818c0)
    intr_thread+0x170(b, 0, 0, 30005393778, 8, 1)

4. Workaround

To work around this issue, specify the "blackhole flag" when adding the route:

    # route add -blackhole 12.1.1.1 127.0.0.1

Note: This will cause the system to return an "ICMP Destination Unreachable" message in response to any packets destined for 12.1.1.1.

5. Resolution

This issue is addressed in the following releases:

SPARC Platform

Solaris 10 with patch 138888-01 or later
OpenSolaris based upon builds snv_83 or later

x86 Platform

Solaris 10 with patch 138889-01 or later
OpenSolaris based upon builds snv_83 or later

For more information on Security Sun Alerts, see 1009886.1.

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References

138888-01
138889-01

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