The mipi_dsi_dcs_write_seq() macro makes a call to
mipi_dsi_dcs_write_buffer() which returns a type ssize_t. The macro
then stores it in an int and checks to see if it's negative. This
could theoretically be a problem if "ssize_t" is larger than "int".
To see the issue, imagine that "ssize_t" is 32-bits and "int" is
16-bits, you could see a problem if there was some code out there that
looked like:
mipi_dsi_dcs_write_seq(dsi, cmd, <32767 bytes as arguments>);
...since we'd get back that 32768 bytes were transferred and 32768
stored in a 16-bit int would look negative.
Though there are no callsites where we'd actually hit this (even if
"int" was only 16-bit), it's cleaner to make the types match so let's
fix it.
Fixes: 2a9e9daf7523 ("drm/mipi-dsi: Introduce mipi_dsi_dcs_write_seq macro")
Reviewed-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
---
(no changes since v3)
Changes in v3:
- Use %zd in print instead of casting errors to int.
Changes in v2:
- New
include/drm/drm_mipi_dsi.h | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index 82b1cc434ea3..70ce0b8cbc68 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -333,18 +333,18 @@ int mipi_dsi_dcs_get_display_brightness_large(struct mipi_dsi_device *dsi,
* @cmd: Command
* @seq: buffer containing data to be transmitted
*/
-#define mipi_dsi_dcs_write_seq(dsi, cmd, seq...) \
- do { \
- static const u8 d[] = { cmd, seq }; \
- struct device *dev = &dsi->dev; \
- int ret; \
- ret = mipi_dsi_dcs_write_buffer(dsi, d, ARRAY_SIZE(d)); \
- if (ret < 0) { \
- dev_err_ratelimited( \
- dev, "sending command %#02x failed: %d\n", \
- cmd, ret); \
- return ret; \
- } \
+#define mipi_dsi_dcs_write_seq(dsi, cmd, seq...) \
+ do { \
+ static const u8 d[] = { cmd, seq }; \
+ struct device *dev = &dsi->dev; \
+ ssize_t ret; \
+ ret = mipi_dsi_dcs_write_buffer(dsi, d, ARRAY_SIZE(d)); \
+ if (ret < 0) { \
+ dev_err_ratelimited( \
+ dev, "sending command %#02x failed: %zd\n", \
+ cmd, ret); \
+ return ret; \
+ } \
} while (0)
/**
--
2.45.0.rc1.225.g2a3ae87e7f-goog
