[PATCH] staging: vme_user: check find_bridge() return value

[Shyam Sunder Reddy Padira]

find_bridge() returns NULL when no matching bridge is found
for a given resource. Some call sites dereference the return
value without verifying it is non-NULL.

Add NULL checks before use to avoid potentail NULL pointer
dereferences.

Signed-off-by: Shyam Sunder Reddy Padira <shyamsunderreddypadira@xxxxxxxxx>
---
 drivers/staging/vme_user/vme.c | 63 ++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/drivers/staging/vme_user/vme.c b/drivers/staging/vme_user/vme.c
index b5c66b66ce32..2ed2f1fe502f 100644
--- a/drivers/staging/vme_user/vme.c
+++ b/drivers/staging/vme_user/vme.c
@@ -82,6 +82,9 @@ void *vme_alloc_consistent(struct vme_resource *resource, size_t size,
 {
 	struct vme_bridge *bridge = find_bridge(resource);
 
+	if (!bridge)
+		return NULL;
+
 	if (!bridge->alloc_consistent) {
 		dev_err(bridge->parent,
 			"alloc_consistent not supported by bridge %s\n",
@@ -107,6 +110,9 @@ void vme_free_consistent(struct vme_resource *resource, size_t size,
 {
 	struct vme_bridge *bridge = find_bridge(resource);
 
+	if (!bridge)
+		return;
+
 	if (!bridge->free_consistent) {
 		dev_err(bridge->parent,
 			"free_consistent not supported by bridge %s\n",
@@ -136,6 +142,9 @@ size_t vme_get_size(struct vme_resource *resource)
 	dma_addr_t buf_base;
 	u32 aspace, cycle, dwidth;
 
+	if (!bridge)
+		return 0;
+
 	switch (resource->type) {
 	case VME_MASTER:
 		retval = vme_master_get(resource, &enabled, &base, &size,
@@ -332,6 +341,9 @@ int vme_slave_set(struct vme_resource *resource, int enabled,
 	struct vme_slave_resource *image;
 	int retval;
 
+	if (!bridge)
+		return 0;
+
 	if (resource->type != VME_SLAVE) {
 		dev_err(bridge->parent, "Not a slave resource\n");
 		return -EINVAL;
@@ -381,6 +393,9 @@ int vme_slave_get(struct vme_resource *resource, int *enabled,
 	struct vme_bridge *bridge = find_bridge(resource);
 	struct vme_slave_resource *image;
 
+	if (!bridge)
+		return 0;
+
 	if (resource->type != VME_SLAVE) {
 		dev_err(bridge->parent, "Not a slave resource\n");
 		return -EINVAL;
@@ -409,6 +424,9 @@ void vme_slave_free(struct vme_resource *resource)
 	struct vme_bridge *bridge = find_bridge(resource);
 	struct vme_slave_resource *slave_image;
 
+	if (!bridge)
+		return;
+
 	if (resource->type != VME_SLAVE) {
 		dev_err(bridge->parent, "Not a slave resource\n");
 		return;
@@ -529,6 +547,9 @@ int vme_master_set(struct vme_resource *resource, int enabled,
 	struct vme_master_resource *image;
 	int retval;
 
+	if (!bridge)
+		return 0;
+
 	if (resource->type != VME_MASTER) {
 		dev_err(bridge->parent, "Not a master resource\n");
 		return -EINVAL;
@@ -579,6 +600,9 @@ int vme_master_get(struct vme_resource *resource, int *enabled,
 	struct vme_bridge *bridge = find_bridge(resource);
 	struct vme_master_resource *image;
 
+	if (!bridge)
+		return 0;
+
 	if (resource->type != VME_MASTER) {
 		dev_err(bridge->parent, "Not a master resource\n");
 		return -EINVAL;
@@ -618,6 +642,9 @@ ssize_t vme_master_read(struct vme_resource *resource, void *buf, size_t count,
 	struct vme_master_resource *image;
 	size_t length;
 
+	if (!bridge)
+		return 0;
+
 	if (!bridge->master_read) {
 		dev_warn(bridge->parent,
 			 "Reading from resource not supported\n");
@@ -667,6 +694,9 @@ ssize_t vme_master_write(struct vme_resource *resource, void *buf,
 	struct vme_master_resource *image;
 	size_t length;
 
+	if (!bridge)
+		return 0;
+
 	if (!bridge->master_write) {
 		dev_warn(bridge->parent, "Writing to resource not supported\n");
 		return -EINVAL;
@@ -718,6 +748,9 @@ unsigned int vme_master_rmw(struct vme_resource *resource, unsigned int mask,
 	struct vme_bridge *bridge = find_bridge(resource);
 	struct vme_master_resource *image;
 
+	if (!bridge)
+		return 0;
+
 	if (!bridge->master_rmw) {
 		dev_warn(bridge->parent, "Writing to resource not supported\n");
 		return -EINVAL;
@@ -753,6 +786,9 @@ int vme_master_mmap_prepare(struct vme_resource *resource,
 	struct vme_master_resource *image;
 	phys_addr_t phys_addr;
 
+	if (!bridge)
+		return 0;
+
 	if (resource->type != VME_MASTER) {
 		dev_err(bridge->parent, "Not a master resource\n");
 		return -EINVAL;
@@ -783,6 +819,9 @@ void vme_master_free(struct vme_resource *resource)
 	struct vme_bridge *bridge = find_bridge(resource);
 	struct vme_master_resource *master_image;
 
+	if (!bridge)
+		return;
+
 	if (resource->type != VME_MASTER) {
 		dev_err(bridge->parent, "Not a master resource\n");
 		return;
@@ -889,6 +928,9 @@ struct vme_dma_list *vme_new_dma_list(struct vme_resource *resource)
 	struct vme_bridge *bridge = find_bridge(resource);
 	struct vme_dma_list *dma_list;
 
+	if (!bridge)
+		return NULL;
+
 	if (resource->type != VME_DMA) {
 		dev_err(bridge->parent, "Not a DMA resource\n");
 		return NULL;
@@ -1173,6 +1215,9 @@ int vme_dma_free(struct vme_resource *resource)
 	struct vme_bridge *bridge = find_bridge(resource);
 	struct vme_dma_resource *ctrlr;
 
+	if (!bridge)
+		return 0;
+
 	if (resource->type != VME_DMA) {
 		dev_err(bridge->parent, "Not a DMA resource\n");
 		return -EINVAL;
@@ -1494,6 +1539,9 @@ int vme_lm_count(struct vme_resource *resource)
 	struct vme_bridge *bridge = find_bridge(resource);
 	struct vme_lm_resource *lm;
 
+	if (!bridge)
+		return 0;
+
 	if (resource->type != VME_LM) {
 		dev_err(bridge->parent, "Not a Location Monitor resource\n");
 		return -EINVAL;
@@ -1525,6 +1573,9 @@ int vme_lm_set(struct vme_resource *resource, unsigned long long lm_base,
 	struct vme_bridge *bridge = find_bridge(resource);
 	struct vme_lm_resource *lm;
 
+	if (!bridge)
+		return 0;
+
 	if (resource->type != VME_LM) {
 		dev_err(bridge->parent, "Not a Location Monitor resource\n");
 		return -EINVAL;
@@ -1561,6 +1612,9 @@ int vme_lm_get(struct vme_resource *resource, unsigned long long *lm_base,
 	struct vme_bridge *bridge = find_bridge(resource);
 	struct vme_lm_resource *lm;
 
+	if (!bridge)
+		return 0;
+
 	if (resource->type != VME_LM) {
 		dev_err(bridge->parent, "Not a Location Monitor resource\n");
 		return -EINVAL;
@@ -1598,6 +1652,9 @@ int vme_lm_attach(struct vme_resource *resource, int monitor,
 	struct vme_bridge *bridge = find_bridge(resource);
 	struct vme_lm_resource *lm;
 
+	if (!bridge)
+		return 0;
+
 	if (resource->type != VME_LM) {
 		dev_err(bridge->parent, "Not a Location Monitor resource\n");
 		return -EINVAL;
@@ -1631,6 +1688,9 @@ int vme_lm_detach(struct vme_resource *resource, int monitor)
 	struct vme_bridge *bridge = find_bridge(resource);
 	struct vme_lm_resource *lm;
 
+	if (!bridge)
+		return 0;
+
 	if (resource->type != VME_LM) {
 		dev_err(bridge->parent, "Not a Location Monitor resource\n");
 		return -EINVAL;
@@ -1664,6 +1724,9 @@ void vme_lm_free(struct vme_resource *resource)
 	struct vme_bridge *bridge = find_bridge(resource);
 	struct vme_lm_resource *lm;
 
+	if (!bridge)
+		return;
+
 	if (resource->type != VME_LM) {
 		dev_err(bridge->parent, "Not a Location Monitor resource\n");
 		return;
-- 
2.43.0