From 46f49b7a223ac7493e7cf619fb583d11edefc2c2 Mon Sep 17 00:00:00 2001 From: Dmitry Torokhov Date: Wed, 2 May 2012 00:13:38 -0700 Subject: [PATCH] Input: serio_raw - signal EFAULT even if read/write partially succeeds When copy_to/from_user fails in the middle of transfer we should not report to the user that read/write partially succeeded but rather report -EFAULT right away, so that application will know that it got its buffers all wrong. If application messed up its buffers we can't trust the data fetched from userspace and successfully written to the device or if data read from the device and transferred to userspace ended up where application expected it to end. If serio_write() fails we still going to report partial writes if failure happens in the middle of the transfer. This is basically a revert of 7a0a27d2ce38aee19a31fee8c12095f586eed393 and 4fa0771138d0b56fe59ab8ab3b1ce9e594484362. Signed-off-by: Dmitry Torokhov --- drivers/input/serio/serio_raw.c | 33 ++++++++++++++++++--------------- 1 file changed, 18 insertions(+), 15 deletions(-) diff --git a/drivers/input/serio/serio_raw.c b/drivers/input/serio/serio_raw.c index 3e243621c0e..59df2e7317a 100644 --- a/drivers/input/serio/serio_raw.c +++ b/drivers/input/serio/serio_raw.c @@ -165,9 +165,9 @@ static ssize_t serio_raw_read(struct file *file, char __user *buffer, struct serio_raw *serio_raw = client->serio_raw; char uninitialized_var(c); ssize_t read = 0; - int error = 0; + int error; - do { + for (;;) { if (serio_raw->dead) return -ENODEV; @@ -179,24 +179,24 @@ static ssize_t serio_raw_read(struct file *file, char __user *buffer, break; while (read < count && serio_raw_fetch_byte(serio_raw, &c)) { - if (put_user(c, buffer++)) { - error = -EFAULT; - goto out; - } + if (put_user(c, buffer++)) + return -EFAULT; read++; } if (read) break; - if (!(file->f_flags & O_NONBLOCK)) + if (!(file->f_flags & O_NONBLOCK)) { error = wait_event_interruptible(serio_raw->wait, serio_raw->head != serio_raw->tail || serio_raw->dead); - } while (!error); + if (error) + return error; + } + } -out: - return read ?: error; + return read; } static ssize_t serio_raw_write(struct file *file, const char __user *buffer, @@ -204,8 +204,7 @@ static ssize_t serio_raw_write(struct file *file, const char __user *buffer, { struct serio_raw_client *client = file->private_data; struct serio_raw *serio_raw = client->serio_raw; - ssize_t written = 0; - int retval; + int retval = 0; unsigned char c; retval = mutex_lock_interruptible(&serio_raw_mutex); @@ -225,16 +224,20 @@ static ssize_t serio_raw_write(struct file *file, const char __user *buffer, retval = -EFAULT; goto out; } + if (serio_write(serio_raw->serio, c)) { - retval = -EIO; + /* Either signal error or partial write */ + if (retval == 0) + retval = -EIO; goto out; } - written++; + + retval++; } out: mutex_unlock(&serio_raw_mutex); - return written ?: retval; + return retval; } static unsigned int serio_raw_poll(struct file *file, poll_table *wait) -- 2.20.1