PATCH i2c: smbus_read_block write out of buffer on noisy bus

[Pasha Orehov <orehovpasha@xxxxxxxxx>]

Hi, all
On i2c_smbus_read_block my device sometimes returns FFs, so kernel
writes results out of buffer and halts. So it may be treated as
security hole too. This code exists since v2.6
Please mitigate me. :)
Pavel

--- i2c-core-smbus-linus.c    2018-06-21 17:04:10.620609631 +0300
+++ i2c-core-smbus.c    2018-06-21 17:22:23.145417235 +0300
@@ -226,7 +226,7 @@
     if (status)
         return status;

-    memcpy(values, &data.block[1], data.block[0]);
+    memcpy(values, &data.block[1], min(data.block[0], sizeof(data)));
     return data.block[0];
 }
 EXPORT_SYMBOL(i2c_smbus_read_block_data);
@@ -494,7 +494,7 @@
             break;
         case I2C_SMBUS_BLOCK_DATA:
         case I2C_SMBUS_BLOCK_PROC_CALL:
-            for (i = 0; i < msg[1].buf[0] + 1; i++)
+            for (i = 0; i < min(sizeof(i2c_smbus_data), msg[1].buf[0]
+ 1); i++)
                 data->block[i] = msg[1].buf[i];
             break;
         }