Issue

• Kernel panic due to a NULL pointer dereference in the dsa_filter kernel module

• Log holds a stack trace similar to the following

crash> log | less
BUG: unable to handle kernel NULL pointer dereference at 00000000000000a8
IP: [<ffffffffa0188c6b>] tb_irpkt_tree_RB_REMOVE+0xeb/0x1d0 [dsa_filter]
PGD fade88067 PUD f7d01d067 PMD 0 
Oops: 0002 [#1] SMP 
last sysfs file: /sys/devices/system/cpu/online
CPU 7 
Modules linked in: gsch(U) redirfs(U) nf_conntrack_ipv6 nf_defrag_ipv6 nf_conntrack_ipv4 nf_defrag_ipv4
 xt_state nf_conntrack ip6table_filter ip6_tables iptable_filter ip_tables vsock(U) ipv6 dsa_filter(P)(
U) uinput ppdev parport_pc parport microcode vmware_balloon sg vmci(U) i2c_piix4 i2c_core shpchp ext4 j
bd2 mbcache sd_mod crc_t10dif sr_mod cdrom vmxnet3 vmw_pvscsi pata_acpi ata_generic ata_piix dm_mirror 
dm_region_hash dm_log dm_mod [last unloaded: speedstep_lib]

Pid: 0, comm: swapper Tainted: P           ---------------    2.6.32-504.8.1.el6.x86_64 #1 VMware, Inc.
 VMware Virtual Platform/440BX Desktop Reference Platform
RIP: 0010:[<ffffffffa0188c6b>]  [<ffffffffa0188c6b>] tb_irpkt_tree_RB_REMOVE+0xeb/0x1d0 [dsa_filter]
RSP: 0018:ffff8800283c37a8  EFLAGS: 00010246
RAX: ffff881026191a10 RBX: ffff881023f43610 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff881026191a10 RDI: ffffffffa01f8e78
RBP: ffff8800283c37b0 R08: 0000000000000001 R09: 6f730c007423007e
R10: 656550656372756f R11: 23007e0071644972 R12: ffffffffa01f8c40
R13: 0000000000000000 R14: ffff8800283c3910 R15: ffff8810247364d0
FS:  0000000000000000(0000) GS:ffff8800283c0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
CR2: 00000000000000a8 CR3: 0000000fadf81000 CR4: 00000000000007e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process swapper (pid: 0, threadinfo ffff881029ba8000, task ffff881029ba7540)
Stack:
 ffff881023f43610 ffff8800283c37d0 ffffffffa01890c6 ffff881023f43610
<d> 0000000000000001 ffff8800283c3850 ffffffffa018a301 ffff8800283c37f0
<d> 0000ffff00000000 ffff881023f43700 ffff881026e9c810 ffff881026e46010