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drm/mipi-dsi: Fix theoretical int overflow in mipi_dsi_generic_write_seq()

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[ Upstream commit 24acbcce5c ]

The mipi_dsi_generic_write_seq() macro makes a call to
mipi_dsi_generic_write() 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_generic_write_seq(dsi, <32768 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: a9015ce593 ("drm/mipi-dsi: Add a mipi_dsi_dcs_write_seq() macro")
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20240514102056.v5.2.Iadb65b8add19ed3ae3ed6425011beb97e380a912@changeid
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240514102056.v5.2.Iadb65b8add19ed3ae3ed6425011beb97e380a912@changeid
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Douglas Anderson 2024-05-14 10:20:52 -07:00 committed by Greg Kroah-Hartman
parent 4e9d95a132
commit 8d869d02a1
1 changed files with 11 additions and 11 deletions
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22
include/drm/drm_mipi_dsi.h
View file

@ -305,17 +305,17 @@ int mipi_dsi_dcs_get_display_brightness_large(struct mipi_dsi_device *dsi,
* @dsi: DSI peripheral device
* @seq: buffer containing the payload
*/
#define mipi_dsi_generic_write_seq(dsi, seq...) \
do { \
static const u8 d[] = { seq }; \
struct device *dev = &dsi->dev; \
int ret; \
ret = mipi_dsi_generic_write(dsi, d, ARRAY_SIZE(d)); \
if (ret < 0) { \
dev_err_ratelimited(dev, "transmit data failed: %d\n", \
ret); \
return ret; \
} \
#define mipi_dsi_generic_write_seq(dsi, seq...) \
do { \
static const u8 d[] = { seq }; \
struct device *dev = &dsi->dev; \
ssize_t ret; \
ret = mipi_dsi_generic_write(dsi, d, ARRAY_SIZE(d)); \
if (ret < 0) { \
dev_err_ratelimited(dev, "transmit data failed: %zd\n", \
ret); \
return ret; \
} \
} while (0)
/**