diff options
| author | Nathan Chancellor <nathan@kernel.org> | 2026-01-05 23:19:26 -0700 |
|---|---|---|
| committer | Tvrtko Ursulin <tursulin@ursulin.net> | 2026-01-09 08:53:27 +0000 |
| commit | 6419fc157e55665dc8680deb1737dc4c53c33f94 (patch) | |
| tree | 3741d7675646af15f94176fc2663104f18f5a5fb /drivers/gpu | |
| parent | ec27500c8f2b65a3be6ce39a5844d6d246d1b2b0 (diff) | |
drm/panic: Ensure drm_panic_type is initialized to a valid value
If a user has set an invalid CONFIG_DRM_PANIC_SCREEN value (such as
"qr_code" without CONFIG_DRM_PANIC_SCREEN_QR_CODE=y due to missing or
incorrect Rust dependencies), there is a panic when accessing
/sys/module/drm/parameters/panic_screen:
[ 12.218375] BUG: unable to handle page fault for address: 0000000796dd8818
[ 12.219737] #PF: supervisor read access in kernel mode
...
[ 12.227167] RIP: 0010:drm_panic_type_get+0x1b/0x30
If drm_panic_type_set() does not find a valid drm_panic_type enumeration
in drm_panic_type_map based on the provided value, it does not change
drm_panic_type from the default -1 value, which is not a valid index for
accessing drm_panic_type_map in drm_panic_type_get(), resulting in the
crash.
Validate the value of CONFIG_DRM_PANIC_SCREEN at boot time via the
return value of drm_panic_type_set() in drm_panic_init() and explicitly
fall back to the default of "user" with a message to the user so that
they can adjust their configuration or fix missing dependencies.
[ 0.800697] Unsupported value for CONFIG_DRM_PANIC_SCREEN ('qr_code'), falling back to 'user'...
Fixes: e85e9ccf3f84 ("drm/panic: Report invalid or unsupported panic modes")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Signed-off-by: Tvrtko Ursulin <tursulin@ursulin.net>
Link: https://lore.kernel.org/r/20260105-drm_panic-handle-invalid-drm_panic_screen-v1-1-55228bd4b0f8@kernel.org
Diffstat (limited to 'drivers/gpu')
| -rw-r--r-- | drivers/gpu/drm/drm_panic.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c index eb7ef17b9c71..0cd574dd9d88 100644 --- a/drivers/gpu/drm/drm_panic.c +++ b/drivers/gpu/drm/drm_panic.c @@ -1072,8 +1072,11 @@ void drm_panic_unregister(struct drm_device *dev) */ void __init drm_panic_init(void) { - if (drm_panic_type == -1) - drm_panic_type_set(CONFIG_DRM_PANIC_SCREEN, NULL); + if (drm_panic_type == -1 && drm_panic_type_set(CONFIG_DRM_PANIC_SCREEN, NULL)) { + pr_warn("Unsupported value for CONFIG_DRM_PANIC_SCREEN ('%s'), falling back to 'user'...\n", + CONFIG_DRM_PANIC_SCREEN); + drm_panic_type = DRM_PANIC_TYPE_USER; + } drm_panic_qr_init(); } |