Re: [PATCH] fix NULL pointer deference crash
From: Greg KH <gregkh@linuxfoundation.org>
Date: 2021-03-31 17:33:08
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dri-devel, lkml
On Wed, Mar 31, 2021 at 07:34:29PM +0300, Hassan Shahbazi wrote:
quoted hunk ↗ jump to hunk
The patch has fixed a NULL pointer deference crash in hiding the cursor. It is verified by syzbot patch tester. Reported by: syzbot https://syzkaller.appspot.com/bug?id=defb47bf56e1c14d5687280c7bb91ce7b608b94b Signed-off-by: Hassan Shahbazi <redacted> --- drivers/video/fbdev/core/fbcon.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c index 44a5cd2f54cc..ee252d1c43c6 100644 --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c@@ -1333,8 +1333,9 @@ static void fbcon_cursor(struct vc_data *vc, int mode) ops->cursor_flash = (mode == CM_ERASE) ? 0 : 1; - ops->cursor(vc, info, mode, get_color(vc, info, c, 1), - get_color(vc, info, c, 0)); + if (ops && ops->cursor)
As ops obviously is not NULL here (you just used it on the line above), why are you checking it again? And what makes curser be NULL here? How can that happen? Also your subject line can use some work, please make it reflect the driver subsystem you are looking at. thanks, greg k-h