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Noralf Trønnes 4d4c2d8991 drm/cma-helper: Fix crash in fbdev error path
Sergey Suloev reported a crash happening in drm_client_dev_hotplug()
when fbdev had failed to register.

[    9.124598] vc4_hdmi 3f902000.hdmi: ASoC: Failed to create component debugfs directory
[    9.147667] vc4_hdmi 3f902000.hdmi: vc4-hdmi-hifi <-> 3f902000.hdmi mapping ok
[    9.155184] vc4_hdmi 3f902000.hdmi: ASoC: no DMI vendor name!
[    9.166544] vc4-drm soc:gpu: bound 3f902000.hdmi (ops vc4_hdmi_ops [vc4])
[    9.173840] vc4-drm soc:gpu: bound 3f806000.vec (ops vc4_vec_ops [vc4])
[    9.181029] vc4-drm soc:gpu: bound 3f004000.txp (ops vc4_txp_ops [vc4])
[    9.188519] vc4-drm soc:gpu: bound 3f400000.hvs (ops vc4_hvs_ops [vc4])
[    9.195690] vc4-drm soc:gpu: bound 3f206000.pixelvalve (ops vc4_crtc_ops [vc4])
[    9.203523] vc4-drm soc:gpu: bound 3f207000.pixelvalve (ops vc4_crtc_ops [vc4])
[    9.215032] vc4-drm soc:gpu: bound 3f807000.pixelvalve (ops vc4_crtc_ops [vc4])
[    9.274785] vc4-drm soc:gpu: bound 3fc00000.v3d (ops vc4_v3d_ops [vc4])
[    9.290246] [drm] Initialized vc4 0.0.0 20140616 for soc:gpu on minor 0
[    9.297464] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[    9.304600] [drm] Driver supports precise vblank timestamp query.
[    9.382856] vc4-drm soc:gpu: [drm:drm_fb_helper_fbdev_setup [drm_kms_helper]] *ERROR* Failed to set fbdev configuration
[   10.404937] Unable to handle kernel paging request at virtual address 00330a656369768a
[   10.441620] [00330a656369768a] address between user and kernel address ranges
[   10.449087] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[   10.454762] Modules linked in: brcmfmac vc4 drm_kms_helper cfg80211 drm rfkill smsc95xx brcmutil usbnet drm_panel_orientation_quirks raspberrypi_hwmon bcm2835_dma crc32_ce pwm_bcm2835 bcm2835_rng virt_dma rng_core i2c_bcm2835 ip_tables x_tables ipv6
[   10.477296] CPU: 2 PID: 45 Comm: kworker/2:1 Not tainted 4.19.0-rc5 #3
[   10.483934] Hardware name: Raspberry Pi 3 Model B Rev 1.2 (DT)
[   10.489966] Workqueue: events output_poll_execute [drm_kms_helper]
[   10.596515] Process kworker/2:1 (pid: 45, stack limit = 0x000000007e8924dc)
[   10.603590] Call trace:
[   10.606259]  drm_client_dev_hotplug+0x5c/0xb0 [drm]
[   10.611303]  drm_kms_helper_hotplug_event+0x30/0x40 [drm_kms_helper]
[   10.617849]  output_poll_execute+0xc4/0x1e0 [drm_kms_helper]
[   10.623616]  process_one_work+0x1c8/0x318
[   10.627695]  worker_thread+0x48/0x428
[   10.631420]  kthread+0xf8/0x128
[   10.634615]  ret_from_fork+0x10/0x18
[   10.638255] Code: 54000220 f9401261 aa1303e0 b4000141 (f9400c21)
[   10.644456] ---[ end trace c75b4a4b0e141908 ]---

The reason for this is that drm_fbdev_cma_init() removes the drm_client
when fbdev registration fails, but it doesn't remove the client from the
drm_device client list. So the client list now has a pointer that points
into the unknown and we have a 'use after free' situation.

Split drm_client_new() into drm_client_init() and drm_client_add() to fix
removal in the error path.

Fixes: 894a677f4b ("drm/cma-helper: Use the generic fbdev emulation")
Reported-by: Sergey Suloev <ssuloev@orpaltech.com>
Cc: Stefan Wahren <stefan.wahren@i2se.com>
Cc: Eric Anholt <eric@anholt.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20181001194536.57756-1-noralf@tronnes.org
2018-10-02 13:03:34 +02:00
arch Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-09-29 14:34:06 -07:00
block blk-mq: I/O and timer unplugs are inverted in blktrace 2018-09-27 13:12:44 -06:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto DMAengine updates for v4.19-rc1 2018-08-18 15:55:59 -07:00
Documentation Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2018-09-28 18:04:50 -07:00
drivers drm/cma-helper: Fix crash in fbdev error path 2018-10-02 13:03:34 +02:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs filesystem-dax for 4.19-rc6 2018-09-30 06:19:38 -07:00
include drm/cma-helper: Fix crash in fbdev error path 2018-10-02 13:03:34 +02:00
init Kbuild updates for v4.19 (2nd) 2018-08-25 13:40:38 -07:00
ipc ipc/shm: properly return EIDRM in shm_lock() 2018-09-04 16:45:02 -07:00
kernel Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-09-29 11:32:03 -07:00
lib lib/Kconfig.debug: fix three typos in help text 2018-09-04 16:45:02 -07:00
LICENSES LICENSES: Add Linux-OpenIB license text 2018-04-27 16:41:53 -06:00
mm mm: slowly shrink slabs with a relatively small number of objects 2018-09-20 22:01:11 +02:00
net ip_tunnel: be careful when accessing the inner header 2018-09-24 12:27:04 -07:00
samples samples/bpf: all XDP samples should unload xdp/bpf prog on SIGTERM 2018-08-16 21:55:32 +02:00
scripts linux-kselftest-4.19-rc5 2018-09-17 07:24:28 +02:00
security Revert "uapi/linux/keyctl.h: don't use C++ reserved keyword as a struct member name" 2018-09-25 13:28:58 +02:00
sound ASoC: Fixes for v4.19 2018-09-17 18:59:21 +02:00
tools powerpc fixes for 4.19 #3 2018-09-28 17:43:32 -07:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt KVM: Remove obsolete kvm_unmap_hva notifier backend 2018-09-07 15:06:02 +02:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.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 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 A trivial fix for auxdisplay 2018-09-30 06:20:33 -07:00
Makefile Linux 4.19-rc6 2018-09-30 07:15:35 -07:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

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.