[PATCH V2] accel/amdxdna: Fix potential NULL pointer dereference of abo->client

[Lizhi Hou <lizhi.hou@amd.com>]

Closing a BO handle clears abo->client, while the underlying GEM object
may remain alive due to internal kernel references. As a result, code
executed after the BO handle is closed may dereference a NULL abo->client
pointer.

Remove accesses to abo->client from code paths that may execute after the
BO handle has been closed.

Fixes: d76856beb4a4 ("accel/amdxdna: Refactor GEM BO handling and add helper APIs for address retrieval")
Signed-off-by: Lizhi Hou <lizhi.hou@amd.com>
---
 drivers/accel/amdxdna/aie2_message.c |  4 ++--
 drivers/accel/amdxdna/amdxdna_gem.c  | 11 +++++++++--
 drivers/accel/amdxdna/amdxdna_gem.h  | 11 +++++++++--
 3 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/drivers/accel/amdxdna/aie2_message.c b/drivers/accel/amdxdna/aie2_message.c
index c4b364801cc0..dfe0fbdf066d 100644
--- a/drivers/accel/amdxdna/aie2_message.c
+++ b/drivers/accel/amdxdna/aie2_message.c
@@ -840,7 +840,7 @@ static struct aie2_exec_msg_ops npu_exec_message_ops = {
 static int aie2_init_exec_req(void *req, struct amdxdna_gem_obj *cmd_abo,
 			      size_t *size, u32 *msg_op)
 {
-	struct amdxdna_dev *xdna = cmd_abo->client->xdna;
+	struct amdxdna_dev *xdna = to_xdna_dev(to_gobj(cmd_abo)->dev);
 	int ret;
 	u32 op;
 
@@ -874,7 +874,7 @@ static int
 aie2_cmdlist_fill_slot(void *slot, struct amdxdna_gem_obj *cmd_abo,
 		       size_t *size, u32 *cmd_op)
 {
-	struct amdxdna_dev *xdna = cmd_abo->client->xdna;
+	struct amdxdna_dev *xdna = to_xdna_dev(to_gobj(cmd_abo)->dev);
 	int ret;
 	u32 op;
 
diff --git a/drivers/accel/amdxdna/amdxdna_gem.c b/drivers/accel/amdxdna/amdxdna_gem.c
index 1275f91ca705..4628a2787265 100644
--- a/drivers/accel/amdxdna/amdxdna_gem.c
+++ b/drivers/accel/amdxdna/amdxdna_gem.c
@@ -198,6 +198,7 @@ amdxdna_gem_destroy_obj(struct amdxdna_gem_obj *abo)
  */
 void *amdxdna_gem_vmap(struct amdxdna_gem_obj *abo)
 {
+	struct amdxdna_dev *xdna = to_xdna_dev(to_gobj(abo)->dev);
 	struct iosys_map map = IOSYS_MAP_INIT_VADDR(NULL);
 	int ret;
 
@@ -210,7 +211,7 @@ void *amdxdna_gem_vmap(struct amdxdna_gem_obj *abo)
 	if (!abo->mem.kva) {
 		ret = drm_gem_vmap(to_gobj(abo), &map);
 		if (ret)
-			XDNA_ERR(abo->client->xdna, "Vmap bo failed, ret %d", ret);
+			XDNA_ERR(xdna, "Vmap bo failed, ret %d", ret);
 		else
 			abo->mem.kva = map.vaddr;
 	}
@@ -354,7 +355,13 @@ static int amdxdna_hmm_register(struct amdxdna_gem_obj *abo,
 	unsigned long nr_pages;
 	int ret;
 
-	if (!amdxdna_pasid_on(abo->client)) {
+	/*
+	 * When PASID is off, amdxdna_gem_obj_open() called amdxdna_dma_map_bo()
+	 * and mem.dma_addr is valid; use the DMA address directly and skip HMM.
+	 * Avoid dereferencing abo->client which may be NULL (cleared in close())
+	 * while internal kernel references are still held.
+	 */
+	if (abo->mem.dma_addr != AMDXDNA_INVALID_ADDR) {
 		/* Need to set uva for heap uva validation */
 		abo->mem.uva = addr;
 		return 0;
diff --git a/drivers/accel/amdxdna/amdxdna_gem.h b/drivers/accel/amdxdna/amdxdna_gem.h
index a35d2f15d32c..1e90e32bf3cd 100644
--- a/drivers/accel/amdxdna/amdxdna_gem.h
+++ b/drivers/accel/amdxdna/amdxdna_gem.h
@@ -88,12 +88,19 @@ u64 amdxdna_gem_dev_addr(struct amdxdna_gem_obj *abo);
 
 static inline u64 amdxdna_dev_bo_offset(struct amdxdna_gem_obj *abo)
 {
-	return amdxdna_gem_dev_addr(abo) - abo->client->xdna->dev_info->dev_mem_base;
+	return amdxdna_gem_dev_addr(abo) - to_xdna_dev(to_gobj(abo)->dev)->dev_info->dev_mem_base;
 }
 
 static inline u64 amdxdna_obj_dma_addr(struct amdxdna_gem_obj *abo)
 {
-	return amdxdna_pasid_on(abo->client) ? amdxdna_gem_uva(abo) : abo->mem.dma_addr;
+	/*
+	 * amdxdna_gem_obj_open() calls amdxdna_dma_map_bo() only when PASID is
+	 * off, leaving mem.dma_addr at AMDXDNA_INVALID_ADDR when PASID is on.
+	 * Avoid dereferencing abo->client, which is cleared to NULL by
+	 * amdxdna_gem_obj_close() while internal kernel references remain.
+	 */
+	return (abo->mem.dma_addr != AMDXDNA_INVALID_ADDR) ?
+		abo->mem.dma_addr : amdxdna_gem_uva(abo);
 }
 
 void amdxdna_umap_put(struct amdxdna_umap *mapp);
-- 
2.34.1