Hello,
Hit this oops a few times while fuzzing the kernel with Trinity in a qemu virtual machine:
[ 133.012360] BUG: unable to handle kernel NULL pointer dereference at (null) [ 133.013015] IP: [<ffffffff814424d0>] drm_lock_free+0x90/0x110 [ 133.013015] PGD 2fed8067 PUD 2fed9067 PMD 0 [ 133.013015] Oops: 0000 [#1] SMP [ 133.013015] CPU 0 [ 133.013015] Pid: 2718, comm: trinity-child20 Not tainted 3.8.0+ #87 Bochs Bochs [ 133.013015] RIP: 0010:[<ffffffff814424d0>] [<ffffffff814424d0>] drm_lock_free+0x90/0x110 [ 133.013015] RSP: 0018:ffff88001400fd28 EFLAGS: 00010292 [ 133.013015] RAX: ffff8800140c2290 RBX: 0000000000000000 RCX: 0000000000000006 [ 133.013015] RDX: 0000000000001580 RSI: ffff8800140c2960 RDI: ffff8800140c2290 [ 133.013015] RBP: ffff88001400fd68 R08: 0000000000000000 R09: 0000000000000000 [ 133.013015] R10: 0000000000000000 R11: 0000000000000001 R12: 000000000055f4ff [ 133.013015] R13: ffff88003b335c58 R14: ffff88003b335cc8 R15: ffff88001400fdd8 [ 133.013015] FS: 00007fb6cb6b6700(0000) GS:ffff88003fc00000(0000) knlGS:0000000000000000 [ 133.013015] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 133.013015] CR2: 0000000000000000 CR3: 000000001402f000 CR4: 00000000000006f0 [ 133.013015] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 133.013015] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 133.013015] Process trinity-child20 (pid: 2718, threadinfo ffff88001400e000, task ffff8800140c2290) [ 133.013015] Stack: [ 133.013015] 2222222222222222 2222222222222222 2222222222222222 2222222222222222 [ 133.013015] ffff88003ca08000 ffff88003a9a4800 fffffffffffffff2 000000004008642b [ 133.013015] ffff88001400fd78 ffffffff814425a2 ffff88001400fe88 ffffffff8143d710 [ 133.013015] Call Trace: [ 133.013015] [<ffffffff814425a2>] drm_unlock+0x52/0x60 [ 133.013015] [<ffffffff8143d710>] drm_ioctl+0x3d0/0x4d0 [ 133.013015] [<ffffffff81442550>] ? drm_lock_free+0x110/0x110 [ 133.013015] [<ffffffff812fb640>] ? avc_has_perm_flags+0x1d0/0x2a0 [ 133.013015] [<ffffffff812fb498>] ? avc_has_perm_flags+0x28/0x2a0 [ 133.013015] [<ffffffff810f5b18>] ? trace_hardirqs_off_caller+0x28/0xd0 [ 133.013015] [<ffffffff810f5bcd>] ? trace_hardirqs_off+0xd/0x10 [ 133.013015] [<ffffffff811b5ff2>] do_vfs_ioctl+0x532/0x580 [ 133.013015] [<ffffffff812fc7d3>] ? file_has_perm+0x83/0xa0 [ 133.013015] [<ffffffff811b609d>] sys_ioctl+0x5d/0xa0 [ 133.013015] [<ffffffff813571de>] ? trace_hardirqs_on_thunk+0x3a/0x3f [ 133.013015] [<ffffffff81ca07e9>] system_call_fastpath+0x16/0x1b [ 133.013015] Code: 00 00 01 00 00 00 4c 89 f7 e8 2d ce 85 00 b8 01 00 00 00 e9 82 00 00 00 0f 1f 00 4c 89 f7 e8 18 ce 85 00 0f 1f 84 00 00 00 00 00 <44> 8b 03 44 89 c1 44 89 45 cc 81 e1 ff ff ff 3f 89 4d d0 44 8b [ 133.013015] RIP [<ffffffff814424d0>] drm_lock_free+0x90/0x110 [ 133.013015] RSP <ffff88001400fd28> [ 133.013015] CR2: 0000000000000000 [ 133.062048] ---[ end trace 3d5401684feb563f ]---
Tommi