char/tpm: Fix unitialized usage of data buffer

This patch fixes information leakage to the userspace by initializing
the data buffer to zero.

Reported-by: Peter Huewe <[e-mail]>
Signed-off-by: Peter Huewe <[e-mail]>
Signed-off-by: Marcel Selhorst <[e-mail]>
[ Also removed the silly "* sizeof(u8)". If that isn't 1, we have way
deeper problems than a simple multiplication can fix. - Linus ]
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/char/tpm/tpm.c

···
 		return -EBUSY;
 	}
 
-	chip->data_buffer = kmalloc(TPM_BUFSIZE * sizeof(u8), GFP_KERNEL);
+	chip->data_buffer = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
 	if (chip->data_buffer == NULL) {
 		clear_bit(0, &chip->is_open);
 		put_device(chip->dev);