1. Instead of multiplying 2 variable of different types. Change to
assign a value of one variable and then multiply the other variable.
2. Add a int variable for multiplier calculation instead of calculating
different types multiplier with dma_addr_t variable directly.
Fixes: 1a64a7aff8da ("drm/mediatek: Fix cursor plane no update")
Signed-off-by: Jason-JH.Lin <jason-jh.lin@xxxxxxxxxxxx>
Reviewed-by: Alexandre Mergnat <amergnat@xxxxxxxxxxxx>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
---
Change in v5:
Add 'coverity issue' in title and code comments.
---
drivers/gpu/drm/mediatek/mtk_drm_gem.c | 9 +++++-
drivers/gpu/drm/mediatek/mtk_drm_plane.c | 39 ++++++++++++++++++------
2 files changed, 38 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
index 9f364df52478..f6632a0fe509 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
@@ -121,7 +121,14 @@ int mtk_drm_gem_dumb_create(struct drm_file *file_priv, struct drm_device *dev,
int ret;
args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
- args->size = args->pitch * args->height;
+
+ /*
+ * Multiply 2 variables of different types,
+ * for example: args->size = args->spacing * args->height;
+ * may cause coverity issue with unintentional overflow.
+ */
+ args->size = args->pitch;
+ args->size *= args->height;
mtk_gem = mtk_drm_gem_create(dev, args->size, false);
if (IS_ERR(mtk_gem))
diff --git a/drivers/gpu/drm/mediatek/mtk_drm_plane.c b/drivers/gpu/drm/mediatek/mtk_drm_plane.c
index db2f70ae060d..5acb03b7c6fe 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_plane.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_plane.c
@@ -141,6 +141,7 @@ static void mtk_plane_update_new_state(struct drm_plane_state *new_state,
dma_addr_t addr;
dma_addr_t hdr_addr = 0;
unsigned int hdr_pitch = 0;
+ int offset;
gem = fb->obj[0];
mtk_gem = to_mtk_gem_obj(gem);
@@ -150,8 +151,15 @@ static void mtk_plane_update_new_state(struct drm_plane_state *new_state,
modifier = fb->modifier;
if (modifier == DRM_FORMAT_MOD_LINEAR) {
- addr += (new_state->src.x1 >> 16) * fb->format->cpp[0];
- addr += (new_state->src.y1 >> 16) * pitch;
+ /*
+ * Using dma_addr_t variable to calculate with multiplier of different types,
+ * for example: addr += (new_state->src.x1 >> 16) * fb->format->cpp[0];
+ * may cause coverity issue with unintentional overflow.
+ */
+ offset = (new_state->src.x1 >> 16) * fb->format->cpp[0];
+ addr += offset;
+ offset = (new_state->src.y1 >> 16) * pitch;
+ addr += offset;
} else {
int width_in_blocks = ALIGN(fb->width, AFBC_DATA_BLOCK_WIDTH)
/ AFBC_DATA_BLOCK_WIDTH;
@@ -159,21 +167,34 @@ static void mtk_plane_update_new_state(struct drm_plane_state *new_state,
/ AFBC_DATA_BLOCK_HEIGHT;
int x_offset_in_blocks = (new_state->src.x1 >> 16) / AFBC_DATA_BLOCK_WIDTH;
int y_offset_in_blocks = (new_state->src.y1 >> 16) / AFBC_DATA_BLOCK_HEIGHT;
- int hdr_size;
+ int hdr_size, hdr_offset;
hdr_pitch = width_in_blocks * AFBC_HEADER_BLOCK_SIZE;
pitch = width_in_blocks * AFBC_DATA_BLOCK_WIDTH *
AFBC_DATA_BLOCK_HEIGHT * fb->format->cpp[0];
hdr_size = ALIGN(hdr_pitch * height_in_blocks, AFBC_HEADER_ALIGNMENT);
+ hdr_offset = hdr_pitch * y_offset_in_blocks +
+ AFBC_HEADER_BLOCK_SIZE * x_offset_in_blocks;
+
+ /*
+ * Using dma_addr_t variable to calculate with multiplier of different types,
+ * for example: addr += hdr_pitch * y_offset_in_blocks;
+ * may cause coverity issue with unintentional overflow.
+ */
+ hdr_addr = addr + hdr_offset;
- hdr_addr = addr + hdr_pitch * y_offset_in_blocks +
- AFBC_HEADER_BLOCK_SIZE * x_offset_in_blocks;
/* The data plane is offset by 1 additional block. */
- addr = addr + hdr_size +
- pitch * y_offset_in_blocks +
- AFBC_DATA_BLOCK_WIDTH * AFBC_DATA_BLOCK_HEIGHT *
- fb->format->cpp[0] * (x_offset_in_blocks + 1);
+ offset = pitch * y_offset_in_blocks +
+ AFBC_DATA_BLOCK_WIDTH * AFBC_DATA_BLOCK_HEIGHT *
+ fb->format->cpp[0] * (x_offset_in_blocks + 1);
+
+ /*
+ * Using dma_addr_t variable to calculate with multiplier of different types,
+ * for example: addr += pitch * y_offset_in_blocks;
+ * may cause coverity issue with unintentional overflow.
+ */
+ addr = addr + hdr_size + offset;
}
mtk_plane_state->pending.enable = true;
--
2.18.0
