* [PATCH] drivers: video: fbcon: fix NULL dereference in fbcon_cursor()
@ 2021-03-12 8:14 Du Cheng
2021-03-12 8:36 ` Greg Kroah-Hartman
0 siblings, 1 reply; 4+ messages in thread
From: Du Cheng @ 2021-03-12 8:14 UTC (permalink / raw
To: Greg Kroah-Hartman
Cc: Daniel Vetter, syzbot+b67aaae8d3a927f68d20, dri-devel, Du Cheng
add null-check on function pointer before dereference on ops->cursor
Reported-by: syzbot+b67aaae8d3a927f68d20@syzkaller.appspotmail.com
Signed-off-by: Du Cheng <ducheng2@gmail.com>
---
drivers/video/fbdev/core/fbcon.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 44a5cd2f54cc..3406067985b1 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -1333,6 +1333,9 @@ static void fbcon_cursor(struct vc_data *vc, int mode)
ops->cursor_flash = (mode == CM_ERASE) ? 0 : 1;
+ if (!ops->cursor)
+ return;
+
ops->cursor(vc, info, mode, get_color(vc, info, c, 1),
get_color(vc, info, c, 0));
}
--
2.27.0
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^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] drivers: video: fbcon: fix NULL dereference in fbcon_cursor()
2021-03-12 8:14 [PATCH] drivers: video: fbcon: fix NULL dereference in fbcon_cursor() Du Cheng
@ 2021-03-12 8:36 ` Greg Kroah-Hartman
2021-03-12 9:13 ` Du Cheng
2021-03-13 0:23 ` Du Cheng
0 siblings, 2 replies; 4+ messages in thread
From: Greg Kroah-Hartman @ 2021-03-12 8:36 UTC (permalink / raw
To: Du Cheng; +Cc: Daniel Vetter, syzbot+b67aaae8d3a927f68d20, dri-devel
On Fri, Mar 12, 2021 at 04:14:21PM +0800, Du Cheng wrote:
> add null-check on function pointer before dereference on ops->cursor
>
> Reported-by: syzbot+b67aaae8d3a927f68d20@syzkaller.appspotmail.com
> Signed-off-by: Du Cheng <ducheng2@gmail.com>
> ---
> drivers/video/fbdev/core/fbcon.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
> index 44a5cd2f54cc..3406067985b1 100644
> --- a/drivers/video/fbdev/core/fbcon.c
> +++ b/drivers/video/fbdev/core/fbcon.c
> @@ -1333,6 +1333,9 @@ static void fbcon_cursor(struct vc_data *vc, int mode)
>
> ops->cursor_flash = (mode == CM_ERASE) ? 0 : 1;
>
> + if (!ops->cursor)
> + return;
> +
> ops->cursor(vc, info, mode, get_color(vc, info, c, 1),
> get_color(vc, info, c, 0));
> }
> --
> 2.27.0
>
Is this the same issue reported here:
https://lore.kernel.org/r/20210307105642.112572-1-h.shahbazi.git@gmail.com
And has syzbot testing shown that this fix does solve the issue?
thanks,
greg k-h
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https://lists.freedesktop.org/mailman/listinfo/dri-devel
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] drivers: video: fbcon: fix NULL dereference in fbcon_cursor()
2021-03-12 8:36 ` Greg Kroah-Hartman
@ 2021-03-12 9:13 ` Du Cheng
2021-03-13 0:23 ` Du Cheng
1 sibling, 0 replies; 4+ messages in thread
From: Du Cheng @ 2021-03-12 9:13 UTC (permalink / raw
To: Greg Kroah-Hartman; +Cc: Daniel Vetter, syzbot+b67aaae8d3a927f68d20, dri-devel
On Fri, Mar 12, 2021 at 09:36:42AM +0100, Greg Kroah-Hartman wrote:
> On Fri, Mar 12, 2021 at 04:14:21PM +0800, Du Cheng wrote:
> > add null-check on function pointer before dereference on ops->cursor
> >
> > Reported-by: syzbot+b67aaae8d3a927f68d20@syzkaller.appspotmail.com
> > Signed-off-by: Du Cheng <ducheng2@gmail.com>
> > ---
> > drivers/video/fbdev/core/fbcon.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
> > index 44a5cd2f54cc..3406067985b1 100644
> > --- a/drivers/video/fbdev/core/fbcon.c
> > +++ b/drivers/video/fbdev/core/fbcon.c
> > @@ -1333,6 +1333,9 @@ static void fbcon_cursor(struct vc_data *vc, int mode)
> >
> > ops->cursor_flash = (mode == CM_ERASE) ? 0 : 1;
> >
> > + if (!ops->cursor)
> > + return;
> > +
> > ops->cursor(vc, info, mode, get_color(vc, info, c, 1),
> > get_color(vc, info, c, 0));
> > }
> > --
> > 2.27.0
> >
>
> Is this the same issue reported here:
> https://lore.kernel.org/r/20210307105642.112572-1-h.shahbazi.git@gmail.com
>
> And has syzbot testing shown that this fix does solve the issue?
>
> thanks,
>
> greg k-h
Hi Greg,
I sent both my patch and that of shahbazi to syzbot to see if they resolve the
bug by the id b67aaae8d3a927f68d20.
I will keep you posted of the outcomes.
Regards,
Du Cheng
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https://lists.freedesktop.org/mailman/listinfo/dri-devel
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] drivers: video: fbcon: fix NULL dereference in fbcon_cursor()
2021-03-12 8:36 ` Greg Kroah-Hartman
2021-03-12 9:13 ` Du Cheng
@ 2021-03-13 0:23 ` Du Cheng
1 sibling, 0 replies; 4+ messages in thread
From: Du Cheng @ 2021-03-13 0:23 UTC (permalink / raw
To: Greg Kroah-Hartman; +Cc: Daniel Vetter, syzbot+b67aaae8d3a927f68d20, dri-devel
On Fri, Mar 12, 2021 at 09:36:42AM +0100, Greg Kroah-Hartman wrote:
> On Fri, Mar 12, 2021 at 04:14:21PM +0800, Du Cheng wrote:
> > add null-check on function pointer before dereference on ops->cursor
> >
> > Reported-by: syzbot+b67aaae8d3a927f68d20@syzkaller.appspotmail.com
> > Signed-off-by: Du Cheng <ducheng2@gmail.com>
> > ---
> > drivers/video/fbdev/core/fbcon.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
> > index 44a5cd2f54cc..3406067985b1 100644
> > --- a/drivers/video/fbdev/core/fbcon.c
> > +++ b/drivers/video/fbdev/core/fbcon.c
> > @@ -1333,6 +1333,9 @@ static void fbcon_cursor(struct vc_data *vc, int mode)
> >
> > ops->cursor_flash = (mode == CM_ERASE) ? 0 : 1;
> >
> > + if (!ops->cursor)
> > + return;
> > +
> > ops->cursor(vc, info, mode, get_color(vc, info, c, 1),
> > get_color(vc, info, c, 0));
> > }
> > --
> > 2.27.0
> >
>
> Is this the same issue reported here:
> https://lore.kernel.org/r/20210307105642.112572-1-h.shahbazi.git@gmail.com
>
> And has syzbot testing shown that this fix does solve the issue?
>
> thanks,
>
> greg k-h
Hi Greg,
After syzbot testing at
https://syzkaller.appspot.com/bug?id=26567b12e74b8791e1db50da6039ee1705e5a7ed
the results showed that shahbazi's patch did not solve this bug, but my patch
passed the syzbot test.
Regards,
Du Cheng
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-03-12 8:14 [PATCH] drivers: video: fbcon: fix NULL dereference in fbcon_cursor() Du Cheng
2021-03-12 8:36 ` Greg Kroah-Hartman
2021-03-12 9:13 ` Du Cheng
2021-03-13 0:23 ` Du Cheng
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