Re: [PATCH] drm/mcde: dsi: Fix invalid pointer dereference if panel cannot be found

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