diff options
| author | Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> | 2020-09-11 07:57:06 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-09-16 14:35:51 +0200 |
| commit | ec0972adecb391a8d8650832263a4790f3bfb4df (patch) | |
| tree | 3ba74018d69ee85776be32e4843c6e3a33549742 | |
| parent | 3c5a87be170aba8ac40982182f812dcff6ed1ad1 (diff) | |
| download | uml-ec0972adecb391a8d8650832263a4790f3bfb4df.tar.gz | |
fbcon: Fix user font detection test at fbcon_resize().
syzbot is reporting OOB read at fbcon_resize() [1], for
commit 39b3cffb8cf31117 ("fbcon: prevent user font height or width change
from causing potential out-of-bounds access") is by error using
registered_fb[con2fb_map[vc->vc_num]]->fbcon_par->p->userfont (which was
set to non-zero) instead of fb_display[vc->vc_num].userfont (which remains
zero for that display).
We could remove tricky userfont flag [2], for we can determine it by
comparing address of the font data and addresses of built-in font data.
But since that commit is failing to fix the original OOB read [3], this
patch keeps the change minimal in case we decide to revert altogether.
[1] https://syzkaller.appspot.com/bug?id=ebcbbb6576958a496500fee9cf7aa83ea00b5920
[2] https://syzkaller.appspot.com/text?tag=Patch&x=14030853900000
[3] https://syzkaller.appspot.com/bug?id=6fba8c186d97cf1011ab17660e633b1cc4e080c9
Reported-by: syzbot <syzbot+b38b1ef6edf0c74a8d97@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Fixes: 39b3cffb8cf31117 ("fbcon: prevent user font height or width change from causing potential out-of-bounds access")
Cc: George Kennedy <george.kennedy@oracle.com>
Link: https://lore.kernel.org/r/f6e3e611-8704-1263-d163-f52c906a4f06@I-love.SAKURA.ne.jp
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/video/fbdev/core/fbcon.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c index 66167830fefd1..dae7ae7f225ae 100644 --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -2203,7 +2203,7 @@ static int fbcon_resize(struct vc_data *vc, unsigned int width, struct fb_var_screeninfo var = info->var; int x_diff, y_diff, virt_w, virt_h, virt_fw, virt_fh; - if (ops->p && ops->p->userfont && FNTSIZE(vc->vc_font.data)) { + if (p->userfont && FNTSIZE(vc->vc_font.data)) { int size; int pitch = PITCH(vc->vc_font.width); |