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[media] lirc_dev: fixes in lirc_dev_fop_read()

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This makes several changes but they're in one function and sort of
related:

"buf" was leaked on error.  The leak if we try to read an invalid
length is the main concern because it could be triggered over and
over.

If the copy_to_user() failed, then the original code returned the
number of bytes remaining.  read() is supposed to be the opposite way,
where we return the number of bytes copied.  I changed it to just return
-EFAULT on errors.

Also I changed the debug output from "-EFAULT" to just "<fail>" because
it isn't -EFAULT necessarily.  And since we go though that path if the
length is invalid now, there was another debug print that I removed.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Reviewed-by: Jarod Wilson <jarod@redhat.com>
Acked-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Dan Carpenter 2010-11-17 02:20:15 -03:00 committed by Mauro Carvalho Chehab
parent 5c769a68be
commit 250f7a5f62
1 changed files with 15 additions and 10 deletions
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25
drivers/media/IR/lirc_dev.c
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@ -647,18 +647,18 @@ ssize_t lirc_dev_fop_read(struct file *file,
if (!buf)
return -ENOMEM;
if (mutex_lock_interruptible(&ir->irctl_lock))
return -ERESTARTSYS;
if (mutex_lock_interruptible(&ir->irctl_lock)) {
ret = -ERESTARTSYS;
goto out_unlocked;
}
if (!ir->attached) {
mutex_unlock(&ir->irctl_lock);
return -ENODEV;
ret = -ENODEV;
goto out_locked;
}
if (length % ir->chunk_size) {
dev_dbg(ir->d.dev, LOGHEAD "read result = -EINVAL\n",
ir->d.name, ir->d.minor);
mutex_unlock(&ir->irctl_lock);
return -EINVAL;
ret = -EINVAL;
goto out_locked;
}
/*
@ -709,18 +709,23 @@ ssize_t lirc_dev_fop_read(struct file *file,
lirc_buffer_read(ir->buf, buf);
ret = copy_to_user((void *)buffer+written, buf,
ir->buf->chunk_size);
written += ir->buf->chunk_size;
if (!ret)
written += ir->buf->chunk_size;
else
ret = -EFAULT;
}
}
remove_wait_queue(&ir->buf->wait_poll, &wait);
set_current_state(TASK_RUNNING);
out_locked:
mutex_unlock(&ir->irctl_lock);
out_unlocked:
kfree(buf);
dev_dbg(ir->d.dev, LOGHEAD "read result = %s (%d)\n",
ir->d.name, ir->d.minor, ret ? "-EFAULT" : "OK", ret);
ir->d.name, ir->d.minor, ret ? "<fail>" : "<ok>", ret);
return ret ? ret : written;
}