hwmon: (pmbus/adm1266) widen blackbox-info buffer to I2C_SMBUS_BLOCK_MAX

adm1266_nvmem_read_blackbox() declares a 5-byte stack buffer and
passes it to i2c_smbus_read_block_data() to retrieve the 4-byte
BLACKBOX_INFO response.  i2c_smbus_read_block_data() does not honour
caller buffer sizes -- it memcpy()s data.block[0] bytes from the
SMBus transaction (where data.block[0] is the length byte returned by
the slave device, up to I2C_SMBUS_BLOCK_MAX = 32):

	memcpy(values, &data.block[1], data.block[0]);

If the device returns any block length above 5, the call overflows
the caller's 5-byte stack buffer before the post-call

	if (ret != 4)
		return -EIO;

check has a chance to reject the response.

Widen the local buffer to I2C_SMBUS_BLOCK_MAX so the helper has room
for any well-formed SMBus block response, matching the convention used
by the other i2c_smbus_read_block_data() callers in this driver.

Fixes: 15609d189302 ("hwmon: (pmbus/adm1266) read blackbox")
Cc: stable@vger.kernel.org
Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
Link: https://lore.kernel.org/r/20260515-adm1266-fixes-v1-2-1c1ea1349cfe@nexthop.ai
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/hwmon/pmbus/adm1266.c b/drivers/hwmon/pmbus/adm1266.c
index a86666c73a5e9c46c44bb58dd90d3639b1e83908..94691dec1359950b3255ffd3dd53cb06682677c1 100644 (file)
--- a/drivers/hwmon/pmbus/adm1266.c
+++ b/drivers/hwmon/pmbus/adm1266.c
@@ -349,7 +349,7 @@ static int adm1266_nvmem_read_blackbox(struct adm1266_data *data, u8 *read_buff)
 {
        int record_count;
        char index;
-       u8 buf[5];
+       u8 buf[I2C_SMBUS_BLOCK_MAX];
        int ret;
 
        ret = i2c_smbus_read_block_data(data->client, ADM1266_BLACKBOX_INFO, buf);