media: em28xx: Fix DualHD disconnect oops

During the duplication of em28xx state for the second tuner pair
a pointer to alt_max_pkt_size_isoc is copied. During tear down
the second tuner is destroyed first and kfrees alt_max_pkt_size_isoc,
then the first tuner is destroyed and kfrees it again. The property
should only be kfree'd if the tuner is PRIMARY_TS.

[  354.888560] ------------[ cut here ]------------
[  354.888562] kernel BUG at mm/slub.c:296!
[  354.888574] invalid opcode: 0000 [#1] SMP NOPTI
[  354.888869] CPU: 1 PID: 19 Comm: kworker/1:0 Not tainted 4.18.0-rc1+ #20
[  354.889140] Hardware name: MSI MS-7A39/B350M GAMING PRO (MS-7A39), BIOS 2.G0 04/27/2018
[  354.889408] Workqueue: usb_hub_wq hub_event
[  354.889679] RIP: 0010:__slab_free+0x217/0x370
[  354.889942] Code: bb c0 e8 07 41 38 c7 72 39 48 83 c4 70 5b 41 5a 41 5c 41 5d 41 5e 41 5f 5d 49 8d 62 f8 c3 f3 90 49 8b 04 24 a8 01 75 f6 eb 82 <0f> 0b 44 89 45 80 48 89 4d 88 e8 aa fa ff ff 85 c0 74 cc e9 b7 fe
[  354.890598] RSP: 0018:ffffb84c41a4fad0 EFLAGS: 00010246
[  354.890934] RAX: ffff948646e85150 RBX: ffff948646e85150 RCX: ffff948646e85150
[  354.891280] RDX: 00000000820001d9 RSI: fffffa8fd01ba140 RDI: ffff94865e807c00
[  354.891649] RBP: ffffb84c41a4fb70 R08: 0000000000000001 R09: ffffffffc059ce21
[  354.892025] R10: ffff948646e85150 R11: 0000000000000001 R12: fffffa8fd01ba140
[  354.892403] R13: ffff948646e85150 R14: ffff94865e807c00 R15: ffff94864c92e0a0
[  354.892780] FS:  0000000000000000(0000) GS:ffff94865ec40000(0000) knlGS:0000000000000000
[  354.893150] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  354.893530] CR2: 00007f4e476da950 CR3: 000000040112c000 CR4: 00000000003406e0
[  354.893917] Call Trace:
[  354.894315]  ? __dev_printk+0x3c/0x80
[  354.894695]  ? _dev_info+0x64/0x80
[  354.895082]  ? em28xx_free_device+0x41/0x50 [em28xx]
[  354.895464]  kfree+0x17a/0x190
[  354.895852]  ? kfree+0x17a/0x190
[  354.896310]  em28xx_free_device+0x41/0x50 [em28xx]
[  354.896698]  em28xx_usb_disconnect+0xfa/0x110 [em28xx]
[  354.897083]  usb_unbind_interface+0x7a/0x270
[  354.897475]  device_release_driver_internal+0x17c/0x250
[  354.897864]  device_release_driver+0x12/0x20
[  354.898252]  bus_remove_device+0xec/0x160
[  354.898639]  device_del+0x13d/0x320
[  354.899018]  ? usb_remove_ep_devs+0x1f/0x30
[  354.899392]  usb_disable_device+0x9e/0x270
[  354.899772]  usb_disconnect+0x92/0x2a0
[  354.900149]  hub_event+0x98e/0x1650
[  354.900519]  ? sched_clock_cpu+0x11/0xa0
[  354.900890]  process_one_work+0x167/0x3f0
[  354.901251]  worker_thread+0x4d/0x460
[  354.901610]  kthread+0x105/0x140
[  354.901964]  ? rescuer_thread+0x360/0x360
[  354.902318]  ? kthread_associate_blkcg+0xa0/0xa0
[  354.902672]  ret_from_fork+0x22/0x40
[  354.903024] Modules linked in: rc_hauppauge em28xx_rc rc_core si2157 lgdt3306a i2c_mux em28xx_dvb dvb_core videobuf2_vmalloc videobuf2_memops videobuf2_common snd_hda_codec_hdmi nls_iso8859_1 edac_mce_amd kvm crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcbc snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_pcm snd_seq_midi aesni_intel snd_seq_midi_event aes_x86_64 snd_rawmidi crypto_simd em28xx cryptd glue_helper asix tveeprom usbnet snd_seq v4l2_common mii videodev snd_seq_device media input_leds snd_timer joydev ccp k10temp wmi_bmof snd soundcore mac_hid sch_fq_codel parport_pc ppdev lp parport ip_tables x_tables vfio_pci vfio_virqfd irqbypass vfio_iommu_type1 vfio nouveau mxm_wmi video i2c_algo_bit ttm drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops i2c_piix4 drm ahci libahci
[  354.905129]  wmi gpio_amdpt gpio_generic hid_generic usbhid hid
[  354.908140] ---[ end trace c230d02716298c34 ]---
[  354.908145] RIP: 0010:__slab_free+0x217/0x370
[  354.908147] Code: bb c0 e8 07 41 38 c7 72 39 48 83 c4 70 5b 41 5a 41 5c 41 5d 41 5e 41 5f 5d 49 8d 62 f8 c3 f3 90 49 8b 04 24 a8 01 75 f6 eb 82 <0f> 0b 44 89 45 80 48 89 4d 88 e8 aa fa ff ff 85 c0 74 cc e9 b7 fe
[  354.908183] RSP: 0018:ffffb84c41a4fad0 EFLAGS: 00010246
[  354.908186] RAX: ffff948646e85150 RBX: ffff948646e85150 RCX: ffff948646e85150
[  354.908189] RDX: 00000000820001d9 RSI: fffffa8fd01ba140 RDI: ffff94865e807c00
[  354.908191] RBP: ffffb84c41a4fb70 R08: 0000000000000001 R09: ffffffffc059ce21
[  354.908193] R10: ffff948646e85150 R11: 0000000000000001 R12: fffffa8fd01ba140
[  354.908195] R13: ffff948646e85150 R14: ffff94865e807c00 R15: ffff94864c92e0a0
[  354.908198] FS:  0000000000000000(0000) GS:ffff94865ec40000(0000) knlGS:0000000000000000
[  354.908201] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  354.908203] CR2: 00007f4e476da950 CR3: 000000016b20a000 CR4: 00000000003406e0
Signed-off-by: Brad Love <brad@nextdimension.cc>
Signed-off-by: Michael Ira Krufky <mkrufky@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/usb/em28xx/em28xx-cards.c

@@ -3376,7 +3376,9 @@ void em28xx_free_device(struct kref *ref)
 	if (!dev->disconnected)
 		em28xx_release_resources(dev);
 
-	kfree(dev->alt_max_pkt_size_isoc);
+	if (dev->ts == PRIMARY_TS)
+		kfree(dev->alt_max_pkt_size_isoc);
+
 	kfree(dev);
 }
 EXPORT_SYMBOL_GPL(em28xx_free_device);