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| author |   Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> | 2020-07-30 19:47:14 +0900 |
|---|---|---|
| committer |   Daniel Vetter <daniel.vetter@ffwll.ch> | 2020-08-04 07:37:23 +0200 |
| commit | d88ca7e1a27eb2df056bbf37ddef62e1c73d37ea (patch) | |
| tree | ab5c93efc1288a746ebeeb3ad98edf1fe022beb3 /include/linux/fb.h | |
| parent | vgaarb: mark vga_tryget static (diff) | |
| download | linux-dev-d88ca7e1a27eb2df056bbf37ddef62e1c73d37ea.tar.xz linux-dev-d88ca7e1a27eb2df056bbf37ddef62e1c73d37ea.zip | |
fbmem: pull fbcon_update_vcs() out of fb_set_var()
syzbot is reporting OOB read bug in vc_do_resize() [1] caused by memcpy()
based on outdated old_{rows,row_size} values, for resize_screen() can
recurse into vc_do_resize() which changes vc->vc_{cols,rows} that outdates
old_{rows,row_size} values which were saved before calling resize_screen().
Daniel Vetter explained that resize_screen() should not recurse into
fbcon_update_vcs() path due to FBINFO_MISC_USEREVENT being still set
when calling resize_screen().
Instead of masking FBINFO_MISC_USEREVENT before calling fbcon_update_vcs(),
we can remove FBINFO_MISC_USEREVENT by calling fbcon_update_vcs() only if
fb_set_var() returned 0. This change assumes that it is harmless to call
fbcon_update_vcs() when fb_set_var() returned 0 without reaching
fb_notifier_call_chain().
[1] https://syzkaller.appspot.com/bug?id=c70c88cfd16dcf6e1d3c7f0ab8648b3144b5b25e
Reported-and-tested-by: syzbot <syzbot+c37a14770d51a085a520@syzkaller.appspotmail.com>
Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: kernel test robot <lkp@intel.com> for missing #include
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/075b7e37-3278-cd7d-31ab-c5073cfa8e92@i-love.sakura.ne.jp
Diffstat (limited to 'include/linux/fb.h')
| -rw-r--r-- | include/linux/fb.h | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/include/linux/fb.h b/include/linux/fb.h index 2b530e6d86e4..850f79e9a7cb 100644 --- a/include/linux/fb.h +++ b/include/linux/fb.h @@ -400,8 +400,6 @@ struct fb_tile_ops { #define FBINFO_HWACCEL_YPAN 0x2000 /* optional */ #define FBINFO_HWACCEL_YWRAP 0x4000 /* optional */ -#define FBINFO_MISC_USEREVENT 0x10000 /* event request - from userspace */ #define FBINFO_MISC_TILEBLITTING 0x20000 /* use tile blitting */ /* A driver may set this flag to indicate that it does want a set_par to be |