From a37960df7eac3cc8094bd1ab84864e9e32c91345 Mon Sep 17 00:00:00 2001 From: Jonas Malaco Date: Thu, 3 Feb 2022 13:49:52 -0300 Subject: [PATCH] eeprom: ee1004: limit i2c reads to I2C_SMBUS_BLOCK_MAX commit c0689e46be23160d925dca95dfc411f1a0462708 upstream. Commit effa453168a7 ("i2c: i801: Don't silently correct invalid transfer size") revealed that ee1004_eeprom_read() did not properly limit how many bytes to read at once. In particular, i2c_smbus_read_i2c_block_data_or_emulated() takes the length to read as an u8. If count == 256 after taking into account the offset and page boundary, the cast to u8 overflows. And this is common when user space tries to read the entire EEPROM at once. To fix it, limit each read to I2C_SMBUS_BLOCK_MAX (32) bytes, already the maximum length i2c_smbus_read_i2c_block_data_or_emulated() allows. Fixes: effa453168a7 ("i2c: i801: Don't silently correct invalid transfer size") Cc: stable@vger.kernel.org Reviewed-by: Heiner Kallweit Signed-off-by: Jonas Malaco Link: https://lore.kernel.org/r/20220203165024.47767-1-jonas@protocubo.io Signed-off-by: Greg Kroah-Hartman --- drivers/misc/eeprom/ee1004.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/misc/eeprom/ee1004.c b/drivers/misc/eeprom/ee1004.c index 252e15ba65e1..d9f90332aaf6 100644 --- a/drivers/misc/eeprom/ee1004.c +++ b/drivers/misc/eeprom/ee1004.c @@ -82,6 +82,9 @@ static ssize_t ee1004_eeprom_read(struct i2c_client *client, char *buf, if (unlikely(offset + count > EE1004_PAGE_SIZE)) count = EE1004_PAGE_SIZE - offset; + if (count > I2C_SMBUS_BLOCK_MAX) + count = I2C_SMBUS_BLOCK_MAX; + status = i2c_smbus_read_i2c_block_data_or_emulated(client, offset, count, buf); dev_dbg(&client->dev, "read %zu@%d --> %d\n", count, offset, status);