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Chris Wilson 7042c2b9a1 drm/i915/fbdev: Serialise early hotplug events with async fbdev config 
commit a45b30a6c5 upstream.

As both the hotplug event and fbdev configuration run asynchronously, it
is possible for them to run concurrently. If configuration fails, we were
freeing the fbdev causing a use-after-free in the hotplug event.

<7>[ 3069.935211] [drm:intel_fb_initial_config [i915]] Not using firmware configuration
<7>[ 3069.935225] [drm:drm_setup_crtcs] looking for cmdline mode on connector 77
<7>[ 3069.935229] [drm:drm_setup_crtcs] looking for preferred mode on connector 77 0
<7>[ 3069.935233] [drm:drm_setup_crtcs] found mode 3200x1800
<7>[ 3069.935236] [drm:drm_setup_crtcs] picking CRTCs for 8192x8192 config
<7>[ 3069.935253] [drm:drm_setup_crtcs] desired mode 3200x1800 set on crtc 43 (0,0)
<7>[ 3069.935323] [drm:intelfb_create [i915]] no BIOS fb, allocating a new one
<4>[ 3069.967737] general protection fault: 0000 [#1] PREEMPT SMP
<0>[ 3069.977453] ---------------------------------
<4>[ 3069.977457] Modules linked in: i915(+) vgem snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul crc32_pclmul ghash_clmulni_intel snd_hda_codec snd_hwdep snd_hda_core snd_pcm r8169 mei_me mii prime_numbers mei i2c_hid pinctrl_geminilake pinctrl_intel [last unloaded: i915]
<4>[ 3069.977492] CPU: 1 PID: 15414 Comm: kworker/1:0 Tainted: G     U          4.14.0-CI-CI_DRM_3388+ #1
<4>[ 3069.977497] Hardware name: Intel Corp. Geminilake/GLK RVP1 DDR4 (05), BIOS GELKRVPA.X64.0062.B30.1708222146 08/22/2017
<4>[ 3069.977508] Workqueue: events output_poll_execute
<4>[ 3069.977512] task: ffff880177734e40 task.stack: ffffc90001fe4000
<4>[ 3069.977519] RIP: 0010:__lock_acquire+0x109/0x1b60
<4>[ 3069.977523] RSP: 0018:ffffc90001fe7bb0 EFLAGS: 00010002
<4>[ 3069.977526] RAX: 6b6b6b6b6b6b6b6b RBX: 0000000000000282 RCX: 0000000000000000
<4>[ 3069.977530] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff880170d4efd0
<4>[ 3069.977534] RBP: ffffc90001fe7c70 R08: 0000000000000001 R09: 0000000000000000
<4>[ 3069.977538] R10: 0000000000000000 R11: ffffffff81899609 R12: ffff880170d4efd0
<4>[ 3069.977542] R13: ffff880177734e40 R14: 0000000000000001 R15: 0000000000000000
<4>[ 3069.977547] FS:  0000000000000000(0000) GS:ffff88017fc80000(0000) knlGS:0000000000000000
<4>[ 3069.977551] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
<4>[ 3069.977555] CR2: 00007f7e8b7bcf04 CR3: 0000000003e0f000 CR4: 00000000003406e0
<4>[ 3069.977559] Call Trace:
<4>[ 3069.977565]  ? mark_held_locks+0x64/0x90
<4>[ 3069.977571]  ? _raw_spin_unlock_irq+0x24/0x50
<4>[ 3069.977575]  ? _raw_spin_unlock_irq+0x24/0x50
<4>[ 3069.977579]  ? trace_hardirqs_on_caller+0xde/0x1c0
<4>[ 3069.977583]  ? _raw_spin_unlock_irq+0x2f/0x50
<4>[ 3069.977588]  ? finish_task_switch+0xa5/0x210
<4>[ 3069.977592]  ? lock_acquire+0xaf/0x200
<4>[ 3069.977596]  lock_acquire+0xaf/0x200
<4>[ 3069.977600]  ? __mutex_lock+0x5e9/0x9b0
<4>[ 3069.977604]  _raw_spin_lock+0x2a/0x40
<4>[ 3069.977608]  ? __mutex_lock+0x5e9/0x9b0
<4>[ 3069.977612]  __mutex_lock+0x5e9/0x9b0
<4>[ 3069.977616]  ? drm_fb_helper_hotplug_event.part.19+0x16/0xa0
<4>[ 3069.977621]  ? drm_fb_helper_hotplug_event.part.19+0x16/0xa0
<4>[ 3069.977625]  drm_fb_helper_hotplug_event.part.19+0x16/0xa0
<4>[ 3069.977630]  output_poll_execute+0x8d/0x180
<4>[ 3069.977635]  process_one_work+0x22e/0x660
<4>[ 3069.977640]  worker_thread+0x48/0x3a0
<4>[ 3069.977644]  ? _raw_spin_unlock_irqrestore+0x4c/0x60
<4>[ 3069.977649]  kthread+0x102/0x140
<4>[ 3069.977653]  ? process_one_work+0x660/0x660
<4>[ 3069.977657]  ? kthread_create_on_node+0x40/0x40
<4>[ 3069.977662]  ret_from_fork+0x27/0x40
<4>[ 3069.977666] Code: 8d 62 f8 c3 49 81 3c 24 e0 fa 3c 82 41 be 00 00 00 00 45 0f 45 f0 83 fe 01 77 86 89 f0 49 8b 44 c4 08 48 85 c0 0f 84 76 ff ff ff <f0> ff 80 38 01 00 00 8b 1d 62 f9 e8 01 45 8b 85 b8 08 00 00 85
<1>[ 3069.977707] RIP: __lock_acquire+0x109/0x1b60 RSP: ffffc90001fe7bb0
<4>[ 3069.977712] ---[ end trace 4ad012eb3af62df7 ]---

In order to keep the dev_priv->ifbdev alive after failure, we have to
avoid the free and leave it empty until we unload the module (which is
less than ideal, but a necessary evil for simplicity). Then we can use
intel_fbdev_sync() to serialise the hotplug event with the configuration.
The serialisation between the two was removed in commit 934458c2c9
("Revert "drm/i915: Fix races on fbdev""), but the use after free is much
older, commit 366e39b4d2 ("drm/i915: Tear down fbdev if initialization
fails")

Fixes: 366e39b4d2 ("drm/i915: Tear down fbdev if initialization fails")
Fixes: 934458c2c9 ("Revert "drm/i915: Fix races on fbdev"")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20171125194155.355-1-chris@chris-wilson.co.uk
(cherry picked from commit ad88d7fc6c)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2017-12-05 11:26:38 +01:00
arch KVM: lapic: Fixup LDR on load in x2apic 2017-12-05 11:26:32 +01:00
block block: Fix a race between blk_cleanup_queue() and timeout handling 2017-11-30 08:40:52 +00:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto crypto: skcipher - Fix skcipher_walk_aead_common 2017-12-05 11:26:30 +01:00
Documentation hwmon: (jc42) optionally try to disable the SMBUS timeout 2017-12-05 11:26:34 +01:00
drivers drm/i915/fbdev: Serialise early hotplug events with async fbdev config 2017-12-05 11:26:38 +01:00
firmware License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fs lockd: lost rollback of set_grace_period() in lockd_down_net() 2017-12-05 11:26:30 +01:00
include include/linux/compiler-clang.h: handle randomizable anonymous structs 2017-12-05 11:26:37 +01:00
init License cleanup: add SPDX license identifiers to some files 2017-11-02 10:04:46 -07:00
ipc License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kernel genirq: Track whether the trigger type has been set 2017-11-30 08:40:52 +00:00
lib lib/mpi: call cond_resched() from mpi_powm() loop 2017-11-30 08:40:39 +00:00
mm mm/hugetlb: fix NULL-pointer dereference on 5-level paging machine 2017-12-05 11:26:30 +01:00
net NFC: fix device-allocation error return 2017-11-30 08:40:55 +00:00
samples License cleanup: add SPDX license identifiers to some files 2017-11-02 10:04:46 -07:00
scripts scripts: add leaking_addresses.pl 2017-11-06 11:46:42 -08:00
security apparmor: fix oops in audit_signal_cb hook 2017-12-05 11:26:31 +01:00
sound ASoC: sun8i-codec: Set the BCLK divider 2017-11-30 08:40:49 +00:00
tools selftests/x86/protection_keys: Fix syscall NR redefinition warnings 2017-11-21 09:49:22 +01:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt Fixes for interrupt controller emulation in ARM/ARM64 and x86, plus a one-liner 2017-11-04 11:44:55 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support to generate LLVM assembly files 2017-04-25 08:13:52 +09:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING [PATCH] update FSF address in COPYING 2005-09-10 10:06:29 -07:00
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS Merge branch 'akpm' (patches from Andrew) 2017-11-09 18:26:51 -08:00
Makefile Linux 4.14.3 2017-11-30 08:41:00 +00:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README 

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.