releases/4.19.34/drm-fb-helper-fix-leaks-in-error-path-of-drm_fb_help.patch

   1 From f850299bc8b21cd71287b1eed79c7aae16812a9c Mon Sep 17 00:00:00 2001
   2 From: Peter Wu <peter@lekensteyn.nl>
   3 Date: Sun, 23 Dec 2018 01:55:07 +0100
   4 Subject: drm/fb-helper: fix leaks in error path of drm_fb_helper_fbdev_setup
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   8
   9 [ Upstream commit 00eb5b0da8d27b3c944bfc959c3344d665caae26 ]
  10
  11 After drm_fb_helper_fbdev_setup calls drm_fb_helper_init,
  12 "dev->fb_helper" will be initialized (and thus drm_fb_helper_fini will
  13 have some effect). After that, drm_fb_helper_initial_config is called
  14 which may call the "fb_probe" driver callback.
  15
  16 This driver callback may call drm_fb_helper_defio_init (as is done by
  17 drm_fb_helper_generic_probe) or set a framebuffer (as is done by bochs)
  18 as documented. These are normally cleaned up on exit by
  19 drm_fb_helper_fbdev_teardown which also calls drm_fb_helper_fini.
  20
  21 If an error occurs after "fb_probe", but before setup is complete, then
  22 calling just drm_fb_helper_fini will leak resources. This was triggered
  23 by df2052cc922 ("bochs: convert to drm_fb_helper_fbdev_setup/teardown"):
  24
  25     [   50.008030] bochsdrmfb: enable CONFIG_FB_LITTLE_ENDIAN to support this framebuffer
  26     [   50.009436] bochs-drm 0000:00:02.0: [drm:drm_fb_helper_fbdev_setup] *ERROR* fbdev: Failed to set configuration (ret=-38)
  27     [   50.011456] [drm] Initialized bochs-drm 1.0.0 20130925 for 0000:00:02.0 on minor 2
  28     [   50.013604] WARNING: CPU: 1 PID: 1 at drivers/gpu/drm/drm_mode_config.c:477 drm_mode_config_cleanup+0x280/0x2a0
  29     [   50.016175] CPU: 1 PID: 1 Comm: swapper/0 Tainted: G                T 4.20.0-rc7 #1
  30     [   50.017732] EIP: drm_mode_config_cleanup+0x280/0x2a0
  31     ...
  32     [   50.023155] Call Trace:
  33     [   50.023155]  ? bochs_kms_fini+0x1e/0x30
  34     [   50.023155]  ? bochs_unload+0x18/0x40
  35
  36 This can be reproduced with QEMU and CONFIG_FB_LITTLE_ENDIAN=n.
  37
  38 Link: https://lkml.kernel.org/r/20181221083226.GI23332@shao2-debian
  39 Link: https://lkml.kernel.org/r/20181223004315.GA11455@al
  40 Fixes: 8741216396b2 ("drm/fb-helper: Add drm_fb_helper_fbdev_setup/teardown()")
  41 Reported-by: kernel test robot <rong.a.chen@intel.com>
  42 Cc: Noralf Trønnes <noralf@tronnes.org>
  43 Signed-off-by: Peter Wu <peter@lekensteyn.nl>
  44 Reviewed-by: Noralf Trønnes <noralf@tronnes.org>
  45 Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
  46 Link: https://patchwork.freedesktop.org/patch/msgid/20181223005507.28328-1-peter@lekensteyn.nl
  47 Signed-off-by: Sasha Levin <sashal@kernel.org>
  48 ---
  49  drivers/gpu/drm/drm_fb_helper.c | 2 +-
  50  1 file changed, 1 insertion(+), 1 deletion(-)
  51
  52 diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
  53 index e65596617239..a0663f44e218 100644
  54 --- a/drivers/gpu/drm/drm_fb_helper.c
  55 +++ b/drivers/gpu/drm/drm_fb_helper.c
  56 @@ -2877,7 +2877,7 @@ int drm_fb_helper_fbdev_setup(struct drm_device *dev,
  57         return 0;
  58
  59  err_drm_fb_helper_fini:
  60 -       drm_fb_helper_fini(fb_helper);
  61 +       drm_fb_helper_fbdev_teardown(dev);
  62
  63         return ret;
  64  }
  65 --
  66 2.19.1
  67