* [PATCH] drm/mcde: dsi: Fix invalid pointer dereference if panel cannot be found
@ 2019-11-18 13:02 Stephan Gerhold
2019-11-20 20:32 ` Linus Walleij
0 siblings, 1 reply; 2+ messages in thread
From: Stephan Gerhold @ 2019-11-18 13:02 UTC (permalink / raw)
To: Linus Walleij
Cc: David Airlie, Daniel Vetter, dri-devel, linux-kernel, Stephan Gerhold
The "panel" pointer is not reset to NULL if of_drm_find_panel()
returns an error. Therefore we later assume that a panel was found,
and try to dereference the error pointer, resulting in:
mcde-dsi a0351000.dsi: failed to find panel try bridge (4294966779)
Unable to handle kernel paging request at virtual address fffffe03
PC is at drm_panel_bridge_add.part.0+0x10/0x5c
LR is at mcde_dsi_bind+0x120/0x464
...
Reset "panel" to NULL to avoid this problem.
Also change the format string of the error to %ld to print
the negative errors correctly. The crash above then becomes:
mcde-dsi a0351000.dsi: failed to find panel try bridge (-517)
mcde-dsi a0351000.dsi: no panel or bridge
...
Fixes: 5fc537bfd000 ("drm/mcde: Add new driver for ST-Ericsson MCDE")
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
---
drivers/gpu/drm/mcde/mcde_dsi.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/mcde/mcde_dsi.c b/drivers/gpu/drm/mcde/mcde_dsi.c
index 03896a1f339a..eb3a855aef9a 100644
--- a/drivers/gpu/drm/mcde/mcde_dsi.c
+++ b/drivers/gpu/drm/mcde/mcde_dsi.c
@@ -924,11 +924,13 @@ static int mcde_dsi_bind(struct device *dev, struct device *master,
for_each_available_child_of_node(dev->of_node, child) {
panel = of_drm_find_panel(child);
if (IS_ERR(panel)) {
- dev_err(dev, "failed to find panel try bridge (%lu)\n",
+ dev_err(dev, "failed to find panel try bridge (%ld)\n",
PTR_ERR(panel));
+ panel = NULL;
+
bridge = of_drm_find_bridge(child);
if (IS_ERR(bridge)) {
- dev_err(dev, "failed to find bridge (%lu)\n",
+ dev_err(dev, "failed to find bridge (%ld)\n",
PTR_ERR(bridge));
return PTR_ERR(bridge);
}
--
2.23.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] drm/mcde: dsi: Fix invalid pointer dereference if panel cannot be found
2019-11-18 13:02 [PATCH] drm/mcde: dsi: Fix invalid pointer dereference if panel cannot be found Stephan Gerhold
@ 2019-11-20 20:32 ` Linus Walleij
0 siblings, 0 replies; 2+ messages in thread
From: Linus Walleij @ 2019-11-20 20:32 UTC (permalink / raw)
To: Stephan Gerhold
Cc: David Airlie, Daniel Vetter, open list:DRM PANEL DRIVERS, linux-kernel
On Mon, Nov 18, 2019 at 2:04 PM Stephan Gerhold <stephan@gerhold.net> wrote:
> The "panel" pointer is not reset to NULL if of_drm_find_panel()
> returns an error. Therefore we later assume that a panel was found,
> and try to dereference the error pointer, resulting in:
>
> mcde-dsi a0351000.dsi: failed to find panel try bridge (4294966779)
> Unable to handle kernel paging request at virtual address fffffe03
> PC is at drm_panel_bridge_add.part.0+0x10/0x5c
> LR is at mcde_dsi_bind+0x120/0x464
> ...
>
> Reset "panel" to NULL to avoid this problem.
> Also change the format string of the error to %ld to print
> the negative errors correctly. The crash above then becomes:
>
> mcde-dsi a0351000.dsi: failed to find panel try bridge (-517)
> mcde-dsi a0351000.dsi: no panel or bridge
> ...
>
> Fixes: 5fc537bfd000 ("drm/mcde: Add new driver for ST-Ericsson MCDE")
> Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Patch applied and pushed to drm-misc-fixes, thanks!
Yours,
Linus Walleij
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