* [PATCH] vgacon: Prevent faulty bootparams.screeninfo from causing harm
@ 2017-08-27 18:23 Jan H. Schönherr
0 siblings, 0 replies; 2+ messages in thread
From: Jan H. Schönherr @ 2017-08-27 18:23 UTC (permalink / raw)
To: linux-fbdev
If a zero for the number of colums or rows manages to slip through,
gotoxy() will underflow vc->vc_pos, causing the next action on the
referenced memory to end with a page fault.
Make the check in vgacon_startup() more pessimistic to prevent that.
Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de>
---
drivers/video/console/vgacon.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
index dc06cb6..445b1dc 100644
--- a/drivers/video/console/vgacon.c
+++ b/drivers/video/console/vgacon.c
@@ -398,9 +398,8 @@ static const char *vgacon_startup(void)
#endif
}
- /* boot_params.screen_info initialized? */
- if ((screen_info.orig_video_mode = 0) &&
- (screen_info.orig_video_lines = 0) &&
+ /* boot_params.screen_info reasonably initialized? */
+ if ((screen_info.orig_video_lines = 0) ||
(screen_info.orig_video_cols = 0))
goto no_vga;
--
2.3.1.dirty
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] vgacon: Prevent faulty bootparams.screeninfo from causing harm
@ 2017-09-04 13:30 Bartlomiej Zolnierkiewicz
0 siblings, 0 replies; 2+ messages in thread
From: Bartlomiej Zolnierkiewicz @ 2017-09-04 13:30 UTC (permalink / raw)
To: linux-fbdev
On Sunday, August 27, 2017 08:23:29 PM Jan H. Schönherr wrote:
> If a zero for the number of colums or rows manages to slip through,
> gotoxy() will underflow vc->vc_pos, causing the next action on the
> referenced memory to end with a page fault.
>
> Make the check in vgacon_startup() more pessimistic to prevent that.
>
> Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de>
Patch queued for 4.14, thanks.
Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics
^ permalink raw reply [flat|nested] 2+ messages in thread
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