From f4e581852753b2d5200f933c9613f9f7c545c1c6 Mon Sep 17 00:00:00 2001
From: Zhou Qingyang <zhou1615@umn.edu>
Date: Wed, 1 Dec 2021 23:13:10 +0800
Subject: drm/radeon/radeon_kms: Fix a NULL pointer dereference in
 radeon_driver_open_kms()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Git-commit: ab50cb9df8896b39aae65c537a30de2c79c19735
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 radeon_driver_open_kms(), radeon_vm_bo_add() is assigned to
vm->ib_bo_va and passes and used in radeon_vm_bo_set_addr(). In
radeon_vm_bo_set_addr(), there is a dereference of vm->ib_bo_va,
which could lead to a NULL pointer dereference on failure of
radeon_vm_bo_add().

Fix this bug by adding a check of vm->ib_bo_va.

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_RADEON=m show no new warnings,
and our static analyzer no longer warns about this code.

Fixes: cc9e67e3d700 ("drm/radeon: fix VM IB handling")
Reviewed-by: Christian König <christian.koenig@amd.com>
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/radeon/radeon_kms.c | 36 ++++++++++++++++-------------
 1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_kms.c b/drivers/gpu/drm/radeon/radeon_kms.c
index 7afe28408085..e2488559cc9f 100644
--- a/drivers/gpu/drm/radeon/radeon_kms.c
+++ b/drivers/gpu/drm/radeon/radeon_kms.c
@@ -648,6 +648,8 @@ void radeon_driver_lastclose_kms(struct drm_device *dev)
 int radeon_driver_open_kms(struct drm_device *dev, struct drm_file *file_priv)
 {
 	struct radeon_device *rdev = dev->dev_private;
+	struct radeon_fpriv *fpriv;
+	struct radeon_vm *vm;
 	int r;
 
 	file_priv->driver_priv = NULL;
@@ -660,8 +662,6 @@ int radeon_driver_open_kms(struct drm_device *dev, struct drm_file *file_priv)
 
 	/* new gpu have virtual address space support */
 	if (rdev->family >= CHIP_CAYMAN) {
-		struct radeon_fpriv *fpriv;
-		struct radeon_vm *vm;
 
 		fpriv = kzalloc(sizeof(*fpriv), GFP_KERNEL);
 		if (unlikely(!fpriv)) {
@@ -672,35 +672,39 @@ int radeon_driver_open_kms(struct drm_device *dev, struct drm_file *file_priv)
 		if (rdev->accel_working) {
 			vm = &fpriv->vm;
 			r = radeon_vm_init(rdev, vm);
-			if (r) {
-				kfree(fpriv);
-				goto out_suspend;
-			}
+			if (r)
+				goto out_fpriv;
 
 			r = radeon_bo_reserve(rdev->ring_tmp_bo.bo, false);
-			if (r) {
-				radeon_vm_fini(rdev, vm);
-				kfree(fpriv);
-				goto out_suspend;
-			}
+			if (r)
+				goto out_vm_fini;
 
 			/* map the ib pool buffer read only into
 			 * virtual address space */
 			vm->ib_bo_va = radeon_vm_bo_add(rdev, vm,
 							rdev->ring_tmp_bo.bo);
+			if (!vm->ib_bo_va) {
+				r = -ENOMEM;
+				goto out_vm_fini;
+			}
+
 			r = radeon_vm_bo_set_addr(rdev, vm->ib_bo_va,
 						  RADEON_VA_IB_OFFSET,
 						  RADEON_VM_PAGE_READABLE |
 						  RADEON_VM_PAGE_SNOOPED);
-			if (r) {
-				radeon_vm_fini(rdev, vm);
-				kfree(fpriv);
-				goto out_suspend;
-			}
+			if (r)
+				goto out_vm_fini;
 		}
 		file_priv->driver_priv = fpriv;
 	}
 
+	if (!r)
+		goto out_suspend;
+
+out_vm_fini:
+	radeon_vm_fini(rdev, vm);
+out_fpriv:
+	kfree(fpriv);
 out_suspend:
 	pm_runtime_mark_last_busy(dev->dev);
 	pm_runtime_put_autosuspend(dev->dev);
-- 
2.38.1