[4.2.0-rc1-00201-g59c3cb5] Regression: kernel NULL pointer dereference

[Jörg Otte]

4.2.0-rc1-00201-g59c3cb5 introducued a null pointer derefence and a
system freeze
when Xorg is started ( 4.2.0-rc1-00062-gc4b5fd3 was fine) :

BUG: unable to handle kernel NULL pointer dereference at 0000000000000009
IP: [<ffffffffbd3447bb>] 0xffffffffbd3447bb
PGD 0
Oops: 0000 [#1] SMP
CPU: 1 PID: 1290 Comm: Xorg Not tainted 4.2.0-rc1-00201-g59c3cb5 #6
Hardware name: FUJITSU LIFEBOOK AH532/FJNBB1C, BIOS Version 1.09 05/22/2012
task: ffff8802149d6c00 ti: ffff880206df4000 task.ti: ffff880206df4000
RIP: 0010:[<ffffffffbd3447bb>]  [<ffffffffbd3447bb>] 0xffffffffbd3447bb
RSP: 0018:ffff880206df7b08  EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88021578f480 RCX: ffff88021578f4d0
RDX: 0000000000000000 RSI: ffff88021630b000 RDI: ffff880214a68000
RBP: ffff88021630b000 R08: ffff88021578f4e0 R09: ffff88021578f4f0
R10: 0000000000003c18 R11: 00000000fffffff2 R12: ffff880214a68000
R13: ffff88021634e800 R14: 0000000000000000 R15: 0000000000000000
FS:  00007ff3caa60880(0000) GS:ffff88021f280000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000009 CR3: 0000000206e07000 CR4: 00000000001407e0
Stack:
 ffff880200010000 ffff880200010000 ffff880200000000 ffff880200000001
 ffff88021578f500 ffffffffbd2df135 ffff880213f71c00 ffff880214a68000
 0000000000000000 ffff880214a70000 0000000000000001 ffff880214a68000
Call Trace:
 [<ffffffffbd2df135>] ? 0xffffffffbd2df135
 [<ffffffffbd2b6ca8>] ? 0xffffffffbd2b6ca8
 [<ffffffffbd33cc7e>] ? 0xffffffffbd33cc7e
 [<ffffffffbd343673>] ? 0xffffffffbd343673
 [<ffffffffbd2d0728>] ? 0xffffffffbd2d0728
 [<ffffffffbd2d088e>] ? 0xffffffffbd2d088e
 [<ffffffffbd2d10c5>] ? 0xffffffffbd2d10c5
 [<ffffffffbd2c6976>] ? 0xffffffffbd2c6976
 [<ffffffffbd2d0fe0>] ? 0xffffffffbd2d0fe0
 [<ffffffffbd0c6a1f>] ? 0xffffffffbd0c6a1f
 [<ffffffffbd0e79e1>] ? 0xffffffffbd0e79e1
 [<ffffffffbd0e7ed1>] ? 0xffffffffbd0e7ed1
 [<ffffffffbd6df557>] ? 0xffffffffbd6df557
Code: 48 89 54 24 20 48 8b 54 24 40 48 89 ee 89 0c 24 4c 89 f9 c7 44
24 18 01 00 00 00 89 44 24 08 e8 bc 1f f7 ff 85 c0 41 89 c7 75 67 <41>
80 7e 09 00 74 56 49 8b 84 24 38 02 00 00 c6 85 d0 08 00 00
RIP  [<ffffffffbd3447bb>] 0xffffffffbd3447bb
 RSP <ffff880206df7b08>
CR2: 0000000000000009
---[ end trace dd0931f7f0d43d12 ] ---