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: sta...@vger.kernel.org
Reported-and-tested-by: syzbot+3d613ae53c0315026...@syzkaller.appspotmail.com
Signed-off-by: Qianqiang Liu <qianqiang....@163.com>
---
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));
