From b16c919f4425807dd751d4a9574dc7c57d97b7eb Mon Sep 17 00:00:00 2001
From: Zhou Qingyang <zhou1615@umn.edu>
Date: Fri, 3 Dec 2021 00:17:36 +0800
Subject: drm/amdgpu: Fix a NULL pointer dereference in
amdgpu_connector_lcd_native_mode()
Git-commit: b220110e4cd442156f36e1d9b4914bb9e87b0d00
Patch-mainline: v5.17-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
In amdgpu_connector_lcd_native_mode(), the return value of
drm_mode_duplicate() is assigned to mode, and there is a dereference
of it in amdgpu_connector_lcd_native_mode(), which will lead to a NULL
pointer dereference on failure of drm_mode_duplicate().
Fix this bug add a check of mode.
This bug was found by a static analyzer. The analysis employs
differential checking to identify inconsistent security operations
(e.g., checks or kfrees) between two code paths and confirms that the
inconsistent operations are not recovered in the current function or
the callers, so they constitute bugs.
Note that, as a bug found by static analysis, it can be a false
positive or hard to trigger. Multiple researchers have cross-reviewed
the bug.
Builds with CONFIG_DRM_AMDGPU=m show no new warnings, and
our static analyzer no longer warns about this code.
Fixes: d38ceaf99ed0 ("drm/amdgpu: add core driver (v4)")
Signed-off-by: Zhou Qingyang <zhou1615@umn.edu>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
index 0de66f59adb8..df1f9b88a53f 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c
@@ -387,6 +387,9 @@ amdgpu_connector_lcd_native_mode(struct drm_encoder *encoder)
native_mode->vdisplay != 0 &&
native_mode->clock != 0) {
mode = drm_mode_duplicate(dev, native_mode);
+ if (!mode)
+ return NULL;
+
mode->type = DRM_MODE_TYPE_PREFERRED | DRM_MODE_TYPE_DRIVER;
drm_mode_set_name(mode);
@@ -401,6 +404,9 @@ amdgpu_connector_lcd_native_mode(struct drm_encoder *encoder)
* simpler.
*/
mode = drm_cvt_mode(dev, native_mode->hdisplay, native_mode->vdisplay, 60, true, false, false);
+ if (!mode)
+ return NULL;
+
mode->type = DRM_MODE_TYPE_PREFERRED | DRM_MODE_TYPE_DRIVER;
DRM_DEBUG_KMS("Adding cvt approximation of native panel mode %s\n", mode->name);
}
--
2.38.1