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Peter Wu 00eb5b0da8 drm/fb-helper: fix leaks in error path of drm_fb_helper_fbdev_setup
After drm_fb_helper_fbdev_setup calls drm_fb_helper_init,
"dev->fb_helper" will be initialized (and thus drm_fb_helper_fini will
have some effect). After that, drm_fb_helper_initial_config is called
which may call the "fb_probe" driver callback.

This driver callback may call drm_fb_helper_defio_init (as is done by
drm_fb_helper_generic_probe) or set a framebuffer (as is done by bochs)
as documented. These are normally cleaned up on exit by
drm_fb_helper_fbdev_teardown which also calls drm_fb_helper_fini.

If an error occurs after "fb_probe", but before setup is complete, then
calling just drm_fb_helper_fini will leak resources. This was triggered
by df2052cc92 ("bochs: convert to drm_fb_helper_fbdev_setup/teardown"):

    [   50.008030] bochsdrmfb: enable CONFIG_FB_LITTLE_ENDIAN to support this framebuffer
    [   50.009436] bochs-drm 0000:00:02.0: [drm:drm_fb_helper_fbdev_setup] *ERROR* fbdev: Failed to set configuration (ret=-38)
    [   50.011456] [drm] Initialized bochs-drm 1.0.0 20130925 for 0000:00:02.0 on minor 2
    [   50.013604] WARNING: CPU: 1 PID: 1 at drivers/gpu/drm/drm_mode_config.c:477 drm_mode_config_cleanup+0x280/0x2a0
    [   50.016175] CPU: 1 PID: 1 Comm: swapper/0 Tainted: G                T 4.20.0-rc7 #1
    [   50.017732] EIP: drm_mode_config_cleanup+0x280/0x2a0
    ...
    [   50.023155] Call Trace:
    [   50.023155]  ? bochs_kms_fini+0x1e/0x30
    [   50.023155]  ? bochs_unload+0x18/0x40

This can be reproduced with QEMU and CONFIG_FB_LITTLE_ENDIAN=n.

Link: https://lkml.kernel.org/r/20181221083226.GI23332@shao2-debian
Link: https://lkml.kernel.org/r/20181223004315.GA11455@al
Fixes: 8741216396 ("drm/fb-helper: Add drm_fb_helper_fbdev_setup/teardown()")
Reported-by: kernel test robot <rong.a.chen@intel.com>
Cc: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Peter Wu <peter@lekensteyn.nl>
Reviewed-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20181223005507.28328-1-peter@lekensteyn.nl
2019-01-08 18:47:46 +01:00
arch arm64 fixes: 2018-11-24 09:42:32 -08:00
block SCSI: fix queue cleanup race before queue initialization is done 2018-11-14 08:19:10 -07:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: user - Zeroize whole structure given to user space 2018-11-09 17:35:43 +08:00
Documentation drm/todo: Better defio support in the generic fbdev emulation 2019-01-08 09:03:52 +01:00
drivers drm/fb-helper: fix leaks in error path of drm_fb_helper_fbdev_setup 2019-01-08 18:47:46 +01:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs NFS client bugfixes for Linux 4.20 2018-11-25 09:19:58 -08:00
include Make some drm headers self-contained with includes and forward declarations 2019-01-07 16:43:24 +01:00
init memblock: stop using implicit alignment to SMP_CACHE_BYTES 2018-10-31 08:54:16 -07:00
ipc ipc: IPCMNI limit check for semmni 2018-10-31 08:54:14 -07:00
kernel swiotlb: Skip cache maintenance on map error 2018-11-21 18:47:58 +01:00
lib XArray updates for 4.20-rc4 2018-11-24 18:44:01 -08:00
LICENSES This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
mm Merge drm/drm-next into drm-intel-next-queued 2018-11-20 13:14:08 +02:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-11-24 09:19:38 -08:00
samples VFIO updates for v4.20 2018-10-31 11:01:38 -07:00
scripts drm-misc-next for v4.21: 2018-11-29 10:28:49 +10:00
security selinux/stable-4.20 PR 20181115 2018-11-15 11:26:09 -06:00
sound Linux 4.20-rc4 2018-11-29 10:34:03 +10:00
tools Power management fixes for 4.20-rc4 2018-11-23 10:52:57 -08:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt Revert "mm, mmu_notifier: annotate mmu notifiers with blockable invalidate callbacks" 2018-10-26 16:25:19 -07:00
.clang-format page cache: Convert find_get_pages_contig to XArray 2018-10-21 10:46:34 -04:00
.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 mailmap: Update email for Punit Agrawal 2018-11-05 10:02:11 +00:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS: change Sparse's maintainer 2018-11-25 09:17:43 -08:00
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: drm: Remove myself as drm-bridge maintainer 2018-12-18 11:42:03 +01:00
Makefile Linux 4.20-rc4 2018-11-25 14:19:31 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -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.

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.