On 9/16/24 03:10, Qianqiang Liu wrote:
syzbot has found a NULL pointer dereference bug in fbcon [1]. This issue is caused by ops->putcs being a NULL pointer. We need to check the pointer before using it. [1] https://syzkaller.appspot.com/bug?extid=3d613ae53c031502687a Cc: stable@xxxxxxxxxxxxxxx Reported-and-tested-by: syzbot+3d613ae53c031502687a@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Qianqiang Liu <qianqiang.liu@xxxxxxx> --- drivers/video/fbdev/core/fbcon.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c index 3f7333dca508..96c1262cc981 100644 --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -1284,7 +1284,7 @@ static void fbcon_putcs(struct vc_data *vc, const u16 *s, unsigned int count, struct fbcon_display *p = &fb_display[vc->vc_num]; struct fbcon_ops *ops = info->fbcon_par; - if (!fbcon_is_inactive(vc, info)) + if (!fbcon_is_inactive(vc, info) && ops->putcs)
I think this patch just hides the real problem. How could putcs have become NULL ? Helge
ops->putcs(vc, info, s, count, real_y(p, ypos), xpos, get_color(vc, info, scr_readw(s), 1), get_color(vc, info, scr_readw(s), 0));
