This is a note to let you know that I've just added the patch titled
i2c: i801: Don't silently correct invalid transfer size
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
i2c-i801-don-t-silently-correct-invalid-transfer-siz.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 6b762ff3523c9f3de12c0a34b82b418a6dcf1006
Author: Heiner Kallweit <hkallweit1@xxxxxxxxx>
Date: Sun Nov 7 22:57:00 2021 +0100
i2c: i801: Don't silently correct invalid transfer size
[ Upstream commit effa453168a7eeb8a562ff4edc1dbf9067360a61 ]
If an invalid block size is provided, reject it instead of silently
changing it to a supported value. Especially critical I see the case of
a write transfer with block length 0. In this case we have no guarantee
that the byte we would write is valid. When silently reducing a read to
32 bytes then we don't return an error and the caller may falsely
assume that we returned the full requested data.
If this change should break any (broken) caller, then I think we should
fix the caller.
Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
Reviewed-by: Jean Delvare <jdelvare@xxxxxxx>
Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index eab6fd6b890eb..5618c1ff34dc3 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -797,6 +797,11 @@ static int i801_block_transaction(struct i801_priv *priv,
int result = 0;
unsigned char hostc;
+ if (read_write == I2C_SMBUS_READ && command == I2C_SMBUS_BLOCK_DATA)
+ data->block[0] = I2C_SMBUS_BLOCK_MAX;
+ else if (data->block[0] < 1 || data->block[0] > I2C_SMBUS_BLOCK_MAX)
+ return -EPROTO;
+
if (command == I2C_SMBUS_I2C_BLOCK_DATA) {
if (read_write == I2C_SMBUS_WRITE) {
/* set I2C_EN bit in configuration register */
@@ -810,16 +815,6 @@ static int i801_block_transaction(struct i801_priv *priv,
}
}
- if (read_write == I2C_SMBUS_WRITE
- || command == I2C_SMBUS_I2C_BLOCK_DATA) {
- if (data->block[0] < 1)
- data->block[0] = 1;
- if (data->block[0] > I2C_SMBUS_BLOCK_MAX)
- data->block[0] = I2C_SMBUS_BLOCK_MAX;
- } else {
- data->block[0] = 32; /* max for SMBus block reads */
- }
-
/* Experience has shown that the block buffer can only be used for
SMBus (not I2C) block transactions, even though the datasheet
doesn't mention this limitation. */
