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Jani Nikula a3520b8992 drm/i915/bios: filter out invalid DDC pins from VBT child devices
The VBT contains the DDC pin to use for specific ports. Alas, sometimes
the field appears to contain bogus data, and while we check for it later
on in intel_gmbus_get_adapter() we fail to check the returned NULL on
errors. Oops results.

The simplest approach seems to be to catch and ignore the bogus DDC pins
already at the VBT parsing phase, reverting to fixed per port default
pins. This doesn't guarantee display working, but at least it prevents
the oops. And we continue to be fuzzed by VBT.

One affected machine is Dell Latitude 5590 where a BIOS upgrade added
invalid DDC pins.

Typical backtrace:

[   35.461411] WARN_ON(!intel_gmbus_is_valid_pin(dev_priv, pin))
[   35.461432] WARNING: CPU: 6 PID: 411 at drivers/gpu/drm/i915/intel_i2c.c:844 intel_gmbus_get_adapter+0x32/0x37 [i915]
[   35.461437] Modules linked in: i915 ahci libahci dm_snapshot dm_bufio dm_raid raid456 async_raid6_recov async_pq raid6_pq async_xor xor async_memcpy async_tx
[   35.461445] CPU: 6 PID: 411 Comm: kworker/u16:2 Not tainted 4.16.0-rc7.x64-g1cda370ffded #1
[   35.461447] Hardware name: Dell Inc. Latitude 5590/0MM81M, BIOS 1.1.9 03/13/2018
[   35.461450] Workqueue: events_unbound async_run_entry_fn
[   35.461465] RIP: 0010:intel_gmbus_get_adapter+0x32/0x37 [i915]
[   35.461467] RSP: 0018:ffff9b4e43d47c40 EFLAGS: 00010286
[   35.461469] RAX: 0000000000000000 RBX: ffff98f90639f800 RCX: ffffffffae051960
[   35.461471] RDX: 0000000000000001 RSI: 0000000000000092 RDI: 0000000000000246
[   35.461472] RBP: ffff98f905410000 R08: 0000004d062a83f6 R09: 00000000000003bd
[   35.461474] R10: 0000000000000031 R11: ffffffffad4eda58 R12: ffff98f905410000
[   35.461475] R13: ffff98f9064c1000 R14: ffff9b4e43d47cf0 R15: ffff98f905410000
[   35.461477] FS:  0000000000000000(0000) GS:ffff98f92e580000(0000) knlGS:0000000000000000
[   35.461479] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   35.461481] CR2: 00007f5682359008 CR3: 00000001b700c005 CR4: 00000000003606e0
[   35.461483] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   35.461484] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   35.461486] Call Trace:
[   35.461501]  intel_hdmi_set_edid+0x37/0x27f [i915]
[   35.461515]  intel_hdmi_detect+0x7c/0x97 [i915]
[   35.461518]  drm_helper_probe_single_connector_modes+0xe1/0x6c0
[   35.461521]  drm_setup_crtcs+0x129/0xa6a
[   35.461523]  ? __switch_to_asm+0x34/0x70
[   35.461525]  ? __switch_to_asm+0x34/0x70
[   35.461527]  ? __switch_to_asm+0x40/0x70
[   35.461528]  ? __switch_to_asm+0x34/0x70
[   35.461529]  ? __switch_to_asm+0x40/0x70
[   35.461531]  ? __switch_to_asm+0x34/0x70
[   35.461532]  ? __switch_to_asm+0x40/0x70
[   35.461534]  ? __switch_to_asm+0x34/0x70
[   35.461536]  __drm_fb_helper_initial_config_and_unlock+0x34/0x46f
[   35.461538]  ? __switch_to_asm+0x40/0x70
[   35.461541]  ? _cond_resched+0x10/0x33
[   35.461557]  intel_fbdev_initial_config+0xf/0x1c [i915]
[   35.461560]  async_run_entry_fn+0x2e/0xf5
[   35.461563]  process_one_work+0x15b/0x364
[   35.461565]  worker_thread+0x2c/0x3a0
[   35.461567]  ? process_one_work+0x364/0x364
[   35.461568]  kthread+0x10c/0x122
[   35.461570]  ? _kthread_create_on_node+0x5d/0x5d
[   35.461572]  ret_from_fork+0x35/0x40
[   35.461574] Code: 74 16 89 f6 48 8d 04 b6 48 c1 e0 05 48 29 f0 48 8d 84 c7 e8 11 00 00 c3 48 c7 c6 b0 19 1e c0 48 c7 c7 64 8a 1c c0 e8 47 88 ed ec <0f> 0b 31 c0 c3 8b 87 a4 04 00 00 80 e4 fc 09 c6 89 b7 a4 04 00
[   35.461604] WARNING: CPU: 6 PID: 411 at drivers/gpu/drm/i915/intel_i2c.c:844 intel_gmbus_get_adapter+0x32/0x37 [i915]
[   35.461606] ---[ end trace 4fe1e63e2dd93373 ]---
[   35.461609] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
[   35.461613] IP: i2c_transfer+0x4/0x86
[   35.461614] PGD 0 P4D 0
[   35.461616] Oops: 0000 [#1] SMP PTI
[   35.461618] Modules linked in: i915 ahci libahci dm_snapshot dm_bufio dm_raid raid456 async_raid6_recov async_pq raid6_pq async_xor xor async_memcpy async_tx
[   35.461624] CPU: 6 PID: 411 Comm: kworker/u16:2 Tainted: G        W        4.16.0-rc7.x64-g1cda370ffded #1
[   35.461625] Hardware name: Dell Inc. Latitude 5590/0MM81M, BIOS 1.1.9 03/13/2018
[   35.461628] Workqueue: events_unbound async_run_entry_fn
[   35.461630] RIP: 0010:i2c_transfer+0x4/0x86
[   35.461631] RSP: 0018:ffff9b4e43d47b30 EFLAGS: 00010246
[   35.461633] RAX: ffff9b4e43d47b6e RBX: 0000000000000005 RCX: 0000000000000001
[   35.461635] RDX: 0000000000000002 RSI: ffff9b4e43d47b80 RDI: 0000000000000000
[   35.461636] RBP: ffff9b4e43d47bd8 R08: 0000004d062a83f6 R09: 00000000000003bd
[   35.461638] R10: 0000000000000031 R11: ffffffffad4eda58 R12: 0000000000000002
[   35.461639] R13: 0000000000000001 R14: ffff9b4e43d47b6f R15: ffff9b4e43d47c07
[   35.461641] FS:  0000000000000000(0000) GS:ffff98f92e580000(0000) knlGS:0000000000000000
[   35.461643] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   35.461645] CR2: 0000000000000010 CR3: 00000001b700c005 CR4: 00000000003606e0
[   35.461646] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   35.461647] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   35.461649] Call Trace:
[   35.461652]  drm_do_probe_ddc_edid+0xb3/0x128
[   35.461654]  drm_get_edid+0xe5/0x38d
[   35.461669]  intel_hdmi_set_edid+0x45/0x27f [i915]
[   35.461684]  intel_hdmi_detect+0x7c/0x97 [i915]
[   35.461687]  drm_helper_probe_single_connector_modes+0xe1/0x6c0
[   35.461689]  drm_setup_crtcs+0x129/0xa6a
[   35.461691]  ? __switch_to_asm+0x34/0x70
[   35.461693]  ? __switch_to_asm+0x34/0x70
[   35.461694]  ? __switch_to_asm+0x40/0x70
[   35.461696]  ? __switch_to_asm+0x34/0x70
[   35.461697]  ? __switch_to_asm+0x40/0x70
[   35.461698]  ? __switch_to_asm+0x34/0x70
[   35.461700]  ? __switch_to_asm+0x40/0x70
[   35.461701]  ? __switch_to_asm+0x34/0x70
[   35.461703]  __drm_fb_helper_initial_config_and_unlock+0x34/0x46f
[   35.461705]  ? __switch_to_asm+0x40/0x70
[   35.461707]  ? _cond_resched+0x10/0x33
[   35.461724]  intel_fbdev_initial_config+0xf/0x1c [i915]
[   35.461727]  async_run_entry_fn+0x2e/0xf5
[   35.461729]  process_one_work+0x15b/0x364
[   35.461731]  worker_thread+0x2c/0x3a0
[   35.461733]  ? process_one_work+0x364/0x364
[   35.461734]  kthread+0x10c/0x122
[   35.461736]  ? _kthread_create_on_node+0x5d/0x5d
[   35.461738]  ret_from_fork+0x35/0x40
[   35.461739] Code: 5c fa e1 ad 48 89 df e8 ea fb ff ff e9 2a ff ff ff 0f 1f 44 00 00 31 c0 e9 43 fd ff ff 31 c0 45 31 e4 e9 c5 fd ff ff 41 54 55 53 <48> 8b 47 10 48 83 78 10 00 74 70 41 89 d4 48 89 f5 48 89 fb 65
[   35.461756] RIP: i2c_transfer+0x4/0x86 RSP: ffff9b4e43d47b30
[   35.461757] CR2: 0000000000000010
[   35.461759] ---[ end trace 4fe1e63e2dd93374 ]---

Based on a patch by Fei Li.

v2: s/reverting/sticking/ (Chris)

Cc: stable@vger.kernel.org
Cc: Fei Li <fei.li@intel.com>
Co-developed-by: Fei Li <fei.li@intel.com>
Reported-by: Pavel Nakonechnyi <zorg1331@gmail.com>
Reported-and-tested-by: Seweryn Kokot <sewkokot@gmail.com>
Reported-and-tested-by: Laszlo Valko <valko@linux.karinthy.hu>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105549
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105961
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180411131519.9091-1-jani.nikula@intel.com
(cherry picked from commit f212bf9abe)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
2018-04-18 14:17:13 +03:00
arch Linux 4.16-rc7 2018-03-28 14:30:41 +10:00
block for-linus-20180302 2018-03-02 09:35:36 -08:00
certs certs/blacklist_nohashes.c: fix const confusion in certs blacklist 2018-02-21 15:35:43 -08:00
crypto X.509: fix NULL dereference when restricting key with unsupported_sig 2018-02-22 14:38:34 +00:00
Documentation Linux 4.16-rc7 2018-03-28 14:30:41 +10:00
drivers drm/i915/bios: filter out invalid DDC pins from VBT child devices 2018-04-18 14:17:13 +03:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs Merge branch 'akpm' (patches from Andrew) 2018-03-22 18:48:43 -07:00
include Merge tag 'drm-amdkfd-next-2018-03-27' of git://people.freedesktop.org/~gabbayo/linux into drm-next 2018-03-28 14:49:19 +10:00
init jump_label: Disable jump labels in __exit code 2018-03-20 08:57:17 +01:00
ipc Revert "mqueue: switch to on-demand creation of internal mount" 2018-03-24 19:34:23 -05:00
kernel Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-03-25 07:34:50 -10:00
lib Merge branch 'akpm' (patches from Andrew) 2018-03-22 18:48:43 -07:00
LICENSES LICENSES: Add MPL-1.1 license 2018-01-06 10:59:44 -07:00
mm mm, thp: do not cause memcg oom for thp 2018-03-22 17:07:02 -07:00
net Two more fixes (in three patches): 2018-03-22 13:19:10 -04:00
samples - do not build samples when cross compiling (Michal Hocko) 2018-02-27 10:39:29 -08:00
scripts Linux 4.16-rc7 2018-03-28 14:30:41 +10:00
security integrity/security: fix digsig.c build error with header file 2018-02-22 20:09:08 -08:00
sound Linux 4.16-rc7 2018-03-28 14:30:41 +10:00
tools Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-03-25 07:36:02 -10:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt kvm/arm fixes for 4.16, take 2 2018-03-15 21:45:37 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore .gitignore: ignore ASN.1 auto generated files 2018-02-14 21:05:38 +01:00
.mailmap mailmap: update Mark Yao's email address 2018-01-04 16:45:09 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS Linux 4.16-rc7 2018-03-28 14:30:41 +10:00
Makefile Linux 4.16-rc7 2018-03-25 12:44:30 -10:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.