| Message ID | ZvLlEpIMQnJcJsla@thinkpad (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] fbcon: Fix a NULL pointer dereference issue in fbcon_putcs | expand |
Hi Qianqiang, On 9/24/24 18:13, Qianqiang Liu wrote: > syzbot has found a NULL pointer dereference bug in fbcon. > > This issue is caused by ops->putcs being a NULL pointer. > We need to ensure it is initialized properly. > > Reported-by: syzbot+3d613ae53c031502687a@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=3d613ae53c031502687a > Tested-by: syzbot+3d613ae53c031502687a@syzkaller.appspotmail.com > Signed-off-by: Qianqiang Liu <qianqiang.liu@163.com> > --- > Changes since v1: > - Initialize ops->putcs by calling set_blitting_type() Thanks a lot tracking this issue down! At first sight your patch seems correct. But could you please document in the patch description what exactly (and why) something goes wrong and how your patch fixes it? E.g. why was opt->putcs missed to be initialized even earlier and why does it need initialization now? You did a good work in producing a reduced testcase. If it's quite small, it's a good idea to even include it in the commit message? Helge > --- > drivers/video/fbdev/core/fbcon.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c > index 2e093535884b..d9abae2516d8 100644 > --- a/drivers/video/fbdev/core/fbcon.c > +++ b/drivers/video/fbdev/core/fbcon.c > @@ -861,6 +861,8 @@ static int set_con2fb_map(int unit, int newidx, int user) > return err; > > fbcon_add_cursor_work(info); > + } else if (vc) { > + set_blitting_type(vc, info); > } > > con2fb_map[unit] = newidx;
diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c index 2e093535884b..d9abae2516d8 100644 --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -861,6 +861,8 @@ static int set_con2fb_map(int unit, int newidx, int user) return err; fbcon_add_cursor_work(info); + } else if (vc) { + set_blitting_type(vc, info); } con2fb_map[unit] = newidx;