Re: [PATCH] drm/komeda: Fix bit check to import to value of proper type

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NIT: This is the second version of this patch so should have "[PATCH v2]" in the subject.

On 27/01/2021 12:34, carsten.haitzler@xxxxxxxxxxxx wrote:
From: Carsten Haitzler <carsten.haitzler@xxxxxxx>

Another issue found by KASAN. The bit finding is buried inside the
dp_for_each_set_bit() macro (that passes on to for_each_set_bit() that
calls the bit stuff. These bit functions want an unsigned long pointer
as input and just dumbly casting leads to out-of-bounds accesses.
This fixes that.

Signed-off-by: Carsten Haitzler <carsten.haitzler@xxxxxxx>
---
  .../gpu/drm/arm/display/include/malidp_utils.h   | 10 ++++++++--
  .../gpu/drm/arm/display/komeda/komeda_pipeline.c | 16 +++++++++++-----
  .../arm/display/komeda/komeda_pipeline_state.c   | 13 ++++++++-----
  3 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/arm/display/include/malidp_utils.h b/drivers/gpu/drm/arm/display/include/malidp_utils.h
index 3bc383d5bf73..8d289cd0b5b8 100644
--- a/drivers/gpu/drm/arm/display/include/malidp_utils.h
+++ b/drivers/gpu/drm/arm/display/include/malidp_utils.h
@@ -12,9 +12,15 @@
#define has_bit(nr, mask) (BIT(nr) & (mask))
  #define has_bits(bits, mask)	(((bits) & (mask)) == (bits))
-
+/*
+#define dp_for_each_set_bit(bit, mask) \
+	for_each_set_bit((bit), (&((unsigned long)(mask))), sizeof(mask) * 8)
+#define dp_for_each_set_bit(bit, mask) \
+	unsigned long __local_mask = mask; \
+	for_each_set_bit((bit), (&__local_mask), sizeof(mask) * 8)
+*/

Commented out code left in - please remove it.

  #define dp_for_each_set_bit(bit, mask) \
-	for_each_set_bit((bit), ((unsigned long *)&(mask)), sizeof(mask) * 8)
+	for_each_set_bit((bit), &(mask), sizeof(mask) * 8)

I'm not really sure if there's much point in this macro now. In practice the uses below are now getting the wrong length (because sizeof(mask) == sizeof(unsigned long) ) but we actually know the size is smaller in most cases, so we could pass a more appropriate value in.

Other than that the changes below look correct to me.

Steve

#define dp_wait_cond(__cond, __tries, __min_range, __max_range) \
  ({							\
diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_pipeline.c b/drivers/gpu/drm/arm/display/komeda/komeda_pipeline.c
index 719a79728e24..a85c8a806334 100644
--- a/drivers/gpu/drm/arm/display/komeda/komeda_pipeline.c
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_pipeline.c
@@ -46,8 +46,9 @@ void komeda_pipeline_destroy(struct komeda_dev *mdev,
  {
  	struct komeda_component *c;
  	int i;
+	unsigned long avail_comps = pipe->avail_comps;
- dp_for_each_set_bit(i, pipe->avail_comps) {
+	dp_for_each_set_bit(i, avail_comps) {
  		c = komeda_pipeline_get_component(pipe, i);
  		komeda_component_destroy(mdev, c);
  	}
@@ -247,6 +248,7 @@ static void komeda_pipeline_dump(struct komeda_pipeline *pipe)
  {
  	struct komeda_component *c;
  	int id;
+	unsigned long avail_comps = pipe->avail_comps;
DRM_INFO("Pipeline-%d: n_layers: %d, n_scalers: %d, output: %s.\n",
  		 pipe->id, pipe->n_layers, pipe->n_scalers,
@@ -258,7 +260,7 @@ static void komeda_pipeline_dump(struct komeda_pipeline *pipe)
  		 pipe->of_output_links[1] ?
  		 pipe->of_output_links[1]->full_name : "none");
- dp_for_each_set_bit(id, pipe->avail_comps) {
+	dp_for_each_set_bit(id, avail_comps) {
  		c = komeda_pipeline_get_component(pipe, id);
komeda_component_dump(c);
@@ -270,8 +272,9 @@ static void komeda_component_verify_inputs(struct komeda_component *c)
  	struct komeda_pipeline *pipe = c->pipeline;
  	struct komeda_component *input;
  	int id;
+	unsigned long supported_inputs = c->supported_inputs;
- dp_for_each_set_bit(id, c->supported_inputs) {
+	dp_for_each_set_bit(id, supported_inputs) {
  		input = komeda_pipeline_get_component(pipe, id);
  		if (!input) {
  			c->supported_inputs &= ~(BIT(id));
@@ -302,8 +305,9 @@ static void komeda_pipeline_assemble(struct komeda_pipeline *pipe)
  	struct komeda_component *c;
  	struct komeda_layer *layer;
  	int i, id;
+	unsigned long avail_comps = pipe->avail_comps;
- dp_for_each_set_bit(id, pipe->avail_comps) {
+	dp_for_each_set_bit(id, avail_comps) {
  		c = komeda_pipeline_get_component(pipe, id);
  		komeda_component_verify_inputs(c);
  	}
@@ -355,13 +359,15 @@ void komeda_pipeline_dump_register(struct komeda_pipeline *pipe,
  {
  	struct komeda_component *c;
  	u32 id;
+	unsigned long avail_comps;
seq_printf(sf, "\n======== Pipeline-%d ==========\n", pipe->id); if (pipe->funcs && pipe->funcs->dump_register)
  		pipe->funcs->dump_register(pipe, sf);
- dp_for_each_set_bit(id, pipe->avail_comps) {
+	avail_comps = pipe->avail_comps;
+	dp_for_each_set_bit(id, avail_comps) {
  		c = komeda_pipeline_get_component(pipe, id);
seq_printf(sf, "\n------%s------\n", c->name);
diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_pipeline_state.c b/drivers/gpu/drm/arm/display/komeda/komeda_pipeline_state.c
index e8b1e15312d8..7640dae7f4bf 100644
--- a/drivers/gpu/drm/arm/display/komeda/komeda_pipeline_state.c
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_pipeline_state.c
@@ -1232,7 +1232,8 @@ komeda_pipeline_unbound_components(struct komeda_pipeline *pipe,
  	struct komeda_pipeline_state *old = priv_to_pipe_st(pipe->obj.state);
  	struct komeda_component_state *c_st;
  	struct komeda_component *c;
-	u32 disabling_comps, id;
+	u32 id;
+	unsigned long disabling_comps;
WARN_ON(!old); @@ -1287,7 +1288,8 @@ bool komeda_pipeline_disable(struct komeda_pipeline *pipe,
  	struct komeda_pipeline_state *old;
  	struct komeda_component *c;
  	struct komeda_component_state *c_st;
-	u32 id, disabling_comps = 0;
+	u32 id;
+	unsigned long disabling_comps;
old = komeda_pipeline_get_old_state(pipe, old_state); @@ -1297,7 +1299,7 @@ bool komeda_pipeline_disable(struct komeda_pipeline *pipe,
  		disabling_comps = old->active_comps &
  				  pipe->standalone_disabled_comps;
- DRM_DEBUG_ATOMIC("PIPE%d: active_comps: 0x%x, disabling_comps: 0x%x.\n",
+	DRM_DEBUG_ATOMIC("PIPE%d: active_comps: 0x%x, disabling_comps: 0x%lx.\n",
  			 pipe->id, old->active_comps, disabling_comps);
dp_for_each_set_bit(id, disabling_comps) {
@@ -1331,13 +1333,14 @@ void komeda_pipeline_update(struct komeda_pipeline *pipe,
  	struct komeda_pipeline_state *new = priv_to_pipe_st(pipe->obj.state);
  	struct komeda_pipeline_state *old;
  	struct komeda_component *c;
-	u32 id, changed_comps = 0;
+	u32 id;
+	unsigned long changed_comps;
old = komeda_pipeline_get_old_state(pipe, old_state); changed_comps = new->active_comps | old->active_comps; - DRM_DEBUG_ATOMIC("PIPE%d: active_comps: 0x%x, changed: 0x%x.\n",
+	DRM_DEBUG_ATOMIC("PIPE%d: active_comps: 0x%x, changed: 0x%lx.\n",
  			 pipe->id, new->active_comps, changed_comps);
dp_for_each_set_bit(id, changed_comps) {


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