From fa2825da6f5d6d45122bd990958970a175fb1aef Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Mon, 23 Jan 2017 17:06:08 -0700 Subject: [PATCH] tpm: Begin the process to deprecate user_read_timer For a long time the cdev read/write interface had this strange idea that userspace had to read the result within 60 seconds otherwise it is discarded. Perhaps this made sense under some older locking regime, but in the modern kernel it is not required and is just dangerous. Since something may be relying on this, double the timeout and print a warning. We can remove the code in a few years, but this should be enough to prevent new users. Suggested-by: James Bottomley Signed-off-by: Jason Gunthorpe Reviewed-by: Jarkko Sakkinen Signed-off-by: Jarkko Sakkinen --- drivers/char/tpm/tpm-dev.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/char/tpm/tpm-dev.c b/drivers/char/tpm/tpm-dev.c index 912ad30be585..02a8850d3a69 100644 --- a/drivers/char/tpm/tpm-dev.c +++ b/drivers/char/tpm/tpm-dev.c @@ -38,6 +38,9 @@ static void user_reader_timeout(unsigned long ptr) { struct file_priv *priv = (struct file_priv *)ptr; + pr_warn("TPM user space timeout is deprecated (pid=%d)\n", + task_tgid_nr(current)); + schedule_work(&priv->work); } @@ -157,7 +160,7 @@ static ssize_t tpm_write(struct file *file, const char __user *buf, mutex_unlock(&priv->buffer_mutex); /* Set a timeout by which the reader must come claim the result */ - mod_timer(&priv->user_read_timer, jiffies + (60 * HZ)); + mod_timer(&priv->user_read_timer, jiffies + (120 * HZ)); return in_size; } -- 2.20.1