[PATCH AUTOSEL 6.11 52/76] usb: typec: ucsi: Don't truncate the reads

[Sasha Levin]

From: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>

[ Upstream commit 1d05c382ddb4e43ce251a50f308df5e42a2f6088 ]

That may silently corrupt the data. Instead, failing attempts
to read more than the interface can handle.

Signed-off-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240816135859.3499351-3-heikki.krogerus@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/usb/typec/ucsi/ucsi.c | 8 ++------
 drivers/usb/typec/ucsi/ucsi.h | 2 ++
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
index 17155ed17fdf8..a8aeda77b1b6b 100644
--- a/drivers/usb/typec/ucsi/ucsi.c
+++ b/drivers/usb/typec/ucsi/ucsi.c
@@ -99,12 +99,8 @@ static int ucsi_run_command(struct ucsi *ucsi, u64 command, u32 *cci,
 
 	*cci = 0;
 
-	/*
-	 * Below UCSI 2.0, MESSAGE_IN was limited to 16 bytes. Truncate the
-	 * reads here.
-	 */
-	if (ucsi->version <= UCSI_VERSION_1_2)
-		size = clamp(size, 0, 16);
+	if (size > UCSI_MAX_DATA_LENGTH(ucsi))
+		return -EINVAL;
 
 	ret = ucsi->ops->sync_control(ucsi, command);
 	if (ret)
diff --git a/drivers/usb/typec/ucsi/ucsi.h b/drivers/usb/typec/ucsi/ucsi.h
index 5a3481d36d7ab..db90b513f78a8 100644
--- a/drivers/usb/typec/ucsi/ucsi.h
+++ b/drivers/usb/typec/ucsi/ucsi.h
@@ -435,6 +435,8 @@ struct ucsi {
 #define UCSI_DELAY_DEVICE_PDOS	BIT(1)	/* Reading PDOs fails until the parter is in PD mode */
 };
 
+#define UCSI_MAX_DATA_LENGTH(u) (((u)->version < UCSI_VERSION_2_0) ? 0x10 : 0xff)
+
 #define UCSI_MAX_SVID		5
 #define UCSI_MAX_ALTMODES	(UCSI_MAX_SVID * 6)
 
-- 
2.43.0