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Lyude Paul ea1de53090 drm/amd/amdgpu/dm: Fix dm_dp_create_fake_mst_encoder() [ Upstream commit `63237f8748` ] [why] Removing connector reusage from DM to match the rest of the tree ended up revealing an issue that was surprisingly subtle. The original amdgpu code for DC that was submitted appears to have left a chunk in dm_dp_create_fake_mst_encoder() that tries to find a "master encoder", the likes of which isn't actually used or stored anywhere. It does so at the wrong time as well by trying to access parts of the drm_connector from the encoder init before it's actually been initialized. This results in a NULL pointer deref on MST hotplugs: [ 160.696613] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 [ 160.697234] PGD 0 P4D 0 [ 160.697814] Oops: 0010 [#1] SMP PTI [ 160.698430] CPU: 2 PID: 64 Comm: kworker/2:1 Kdump: loaded Tainted: G O 4.19.0Lyude-Test+ #2 [ 160.699020] Hardware name: HP HP ZBook 15 G4/8275, BIOS P70 Ver. 01.22 05/17/2018 [ 160.699672] Workqueue: events_long drm_dp_mst_link_probe_work [drm_kms_helper] [ 160.700322] RIP: 0010: (null) [ 160.700920] Code: Bad RIP value. [ 160.701541] RSP: 0018:ffffc9000029fc78 EFLAGS: 00010206 [ 160.702183] RAX: 0000000000000000 RBX: ffff8804440ed468 RCX: ffff8804440e9158 [ 160.702778] RDX: 0000000000000000 RSI: ffff8804556c5700 RDI: ffff8804440ed000 [ 160.703408] RBP: ffff880458e21800 R08: 0000000000000002 R09: 000000005fca0a25 [ 160.704002] R10: ffff88045a077a3d R11: ffff88045a077a3c R12: ffff8804440ed000 [ 160.704614] R13: ffff880458e21800 R14: ffff8804440e9000 R15: ffff8804440e9000 [ 160.705260] FS: 0000000000000000(0000) GS:ffff88045f280000(0000) knlGS:0000000000000000 [ 160.705854] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 160.706478] CR2: ffffffffffffffd6 CR3: 000000000200a001 CR4: 00000000003606e0 [ 160.707124] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 160.707724] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 160.708372] Call Trace: [ 160.708998] ? dm_dp_add_mst_connector+0xed/0x1d0 [amdgpu] [ 160.709625] ? drm_dp_add_port+0x2fa/0x470 [drm_kms_helper] [ 160.710284] ? wake_up_q+0x54/0x70 [ 160.710877] ? __mutex_unlock_slowpath.isra.18+0xb3/0x110 [ 160.711512] ? drm_dp_dpcd_access+0xe7/0x110 [drm_kms_helper] [ 160.712161] ? drm_dp_send_link_address+0x155/0x1e0 [drm_kms_helper] [ 160.712762] ? drm_dp_check_and_send_link_address+0xa3/0xd0 [drm_kms_helper] [ 160.713408] ? drm_dp_mst_link_probe_work+0x4b/0x80 [drm_kms_helper] [ 160.714013] ? process_one_work+0x1a1/0x3a0 [ 160.714667] ? worker_thread+0x30/0x380 [ 160.715326] ? wq_update_unbound_numa+0x10/0x10 [ 160.715939] ? kthread+0x112/0x130 [ 160.716591] ? kthread_create_worker_on_cpu+0x70/0x70 [ 160.717262] ? ret_from_fork+0x35/0x40 [ 160.717886] Modules linked in: amdgpu(O) vfat fat snd_hda_codec_generic joydev i915 chash gpu_sched ttm i2c_algo_bit drm_kms_helper snd_hda_codec_hdmi hp_wmi syscopyarea iTCO_wdt sysfillrect sparse_keymap sysimgblt fb_sys_fops snd_hda_intel usbhid wmi_bmof drm snd_hda_codec btusb snd_hda_core intel_rapl btrtl x86_pkg_temp_thermal btbcm btintel coretemp snd_pcm crc32_pclmul bluetooth psmouse snd_timer snd pcspkr i2c_i801 mei_me i2c_core soundcore mei tpm_tis wmi tpm_tis_core hp_accel ecdh_generic lis3lv02d tpm video rfkill acpi_pad input_polldev hp_wireless pcc_cpufreq crc32c_intel serio_raw tg3 xhci_pci xhci_hcd [last unloaded: amdgpu] [ 160.720141] CR2: 0000000000000000 Somehow the connector reusage DM was using for MST connectors managed to paper over this issue entirely; hence why this was never caught until now. [how] Since this code isn't used anywhere and seems useless anyway, we can just drop it entirely. This appears to fix the issue on my HP ZBook with an AMD WX4150. Signed-off-by: Lyude Paul <lyude@redhat.com> Reviewed-by: Harry Wentland <harry.wentland@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com> Signed-off-by: Sasha Levin <sashal@kernel.org>		2018-11-27 16:13:05 +01:00
arch	arm64: dts: renesas: condor: switch from EtherAVB to GEther	2018-11-27 16:13:04 +01:00
block	block: Clear kernel memory before copying to user	2018-11-27 16:13:05 +01:00
certs	export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR()	2018-08-22 23:21:44 +09:00
crypto	crypto: user - fix leaking uninitialized memory to userspace	2018-11-21 09:19:24 +01:00
Documentation	x86/earlyprintk: Add a force option for pciserial device	2018-11-27 16:13:00 +01:00
drivers	drm/amd/amdgpu/dm: Fix dm_dp_create_fake_mst_encoder()	2018-11-27 16:13:05 +01:00
firmware	kbuild: remove all dummy assignments to obj-	2017-11-18 11:46:06 +09:00
fs	fs/exofs: fix potential memory leak in mount option parsing	2018-11-27 16:13:00 +01:00
include	mtd: nand: Fix nanddev_pos_next_page() kernel-doc header	2018-11-27 16:13:05 +01:00
init	Kbuild updates for v4.19 (2nd)	2018-08-25 13:40:38 -07:00
ipc	ipc/shm.c: use ERR_CAST() for shm_lock() error return	2018-10-05 16:32:04 -07:00
kernel	bpf: fix bpf_prog_get_info_by_fd to return 0 func_lens for unpriv	2018-11-27 16:13:03 +01:00
lib	lib/raid6: Fix arm64 test build	2018-11-27 16:13:05 +01:00
LICENSES	LICENSES: Remove CC-BY-SA-4.0 license text	2018-10-18 11:28:50 +02:00
mm	mm/swapfile.c: use kvzalloc for swap_info_struct allocation	2018-11-21 09:19:24 +01:00
net	netfilter: nft_compat: ebtables 'nat' table is normal chain type	2018-11-27 16:13:03 +01:00
samples	samples: disable CONFIG_SAMPLES for UML	2018-10-11 02:15:46 +09:00
scripts	scripts/spdxcheck.py: make python3 compliant	2018-11-21 09:19:25 +01:00
security	apparmor: Fix uninitialized value in aa_split_fqname	2018-11-27 16:13:00 +01:00
sound	ASoC: sta32x: set ->component pointer in private struct	2018-11-13 11:08:42 -08:00
tools	perf symbols: Set PLT entry/header sizes properly on Sparc	2018-11-27 16:13:00 +01:00
usr	initramfs: move gen_initramfs_list.sh from scripts/ to usr/	2018-08-22 23:21:44 +09:00
virt	KVM: arm64: Fix caching of host MDCR_EL2 value	2018-11-13 11:08:47 -08:00
.clang-format	clang-format: Set IndentWrappedFunctionNames false	2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes	.gitattributes: set git diff driver for C source code files	2016-10-07 18:46:30 -07:00
.gitignore	Kbuild updates for v4.17 (2nd)	2018-04-15 17:21:30 -07:00
.mailmap	libnvdimm-for-4.19_misc	2018-08-25 18:13:10 -07:00
COPYING	COPYING: use the new text with points to the license files	2018-03-23 12:41:45 -06:00
CREDITS	9p: remove Ron Minnich from MAINTAINERS	2018-08-17 16:20:26 -07:00
Kbuild	Kbuild updates for v4.15	2017-11-17 17:45:29 -08:00
Kconfig	kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt	2018-08-02 08:06:55 +09:00
MAINTAINERS	MAINTAINERS: Add an entry for the code of conduct	2018-10-22 07:33:36 +01:00
Makefile	Linux 4.19.4	2018-11-23 08:17:07 +01:00
README	Docs: Added a pointer to the formatted docs to README	2018-03-21 09:02:53 -06:00

README

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

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.