[i2c] [PATCH 04/13] scx200_acb: Fix the block transactions

[Jean Delvare]

The scx200_acb i2c bus driver pretends to support SMBus block
transactions, but in fact it implements the more simple I2C block
transactions. Additionally, it lacks sanity checks on the length
of the block transactions, which could lead to a buffer overrun.

This fixes an oops reported by Alexander Atanasov:
http://marc.theaimsgroup.com/?l=linux-kernel&m=114970382125094

Thanks to Ben Gardner for fixing my bugs :)

Signed-off-by: Jean Delvare <khali at linux-fr.org>
---
 drivers/i2c/busses/scx200_acb.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- linux-2.6.17-git.orig/drivers/i2c/busses/scx200_acb.c	2006-06-21 20:48:46.000000000 +0200
+++ linux-2.6.17-git/drivers/i2c/busses/scx200_acb.c	2006-06-21 21:25:55.000000000 +0200
@@ -307,8 +307,12 @@
 		buffer = (u8 *)&cur_word;
 		break;
 
-	case I2C_SMBUS_BLOCK_DATA:
+	case I2C_SMBUS_I2C_BLOCK_DATA:
+		if (rw == I2C_SMBUS_READ)
+			data->block[0] = I2C_SMBUS_BLOCK_MAX; /* For now */
 		len = data->block[0];
+		if (len == 0 || len > I2C_SMBUS_BLOCK_MAX)
+			return -EINVAL;
 		buffer = &data->block[1];
 		break;
 
@@ -372,7 +376,7 @@
 {
 	return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
 	       I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |
-	       I2C_FUNC_SMBUS_BLOCK_DATA;
+	       I2C_FUNC_SMBUS_I2C_BLOCK;
 }
 
 /* For now, we only handle combined mode (smbus) */

-- 
Jean Delvare