diff options
| author | Ian Abbott <abbotti@mev.co.uk> | 2013-02-27 10:56:19 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-03-04 06:03:39 +0800 |
| commit | 9cb9a5913b9217b8ac94d06905a8a27afe3ea0a2 (patch) | |
| tree | f287a9f94822c12d3347e44b41c98963c134c037 | |
| parent | 30f3a0a711a2d86050c333b3cd2128fc8e0787f7 (diff) | |
staging: comedi: check s->async for poll(), read() and write()
commit cc400e185c07c15a42d2635995f422de5b94b696 upstream.
Some low-level comedi drivers (incorrectly) point `dev->read_subdev` or
`dev->write_subdev` to a subdevice that does not support asynchronous
commands. Comedi's poll(), read() and write() file operation handlers
assume these subdevices do support asynchronous commands. In
particular, they assume `s->async` is valid (where `s` points to the
read or write subdevice), which it won't be if it has been set
incorrectly. This can lead to a NULL pointer dereference.
Check `s->async` is non-NULL in `comedi_poll()`, `comedi_read()` and
`comedi_write()` to avoid the bug.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/staging/comedi/comedi_fops.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index 8f14c42c1349..6894b3e0073e 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -1779,7 +1779,7 @@ static unsigned int comedi_poll(struct file *file, poll_table *wait) mask = 0; read_subdev = comedi_get_read_subdevice(dev_file_info); - if (read_subdev) { + if (read_subdev && read_subdev->async) { poll_wait(file, &read_subdev->async->wait_head, wait); if (!read_subdev->busy || comedi_buf_read_n_available(read_subdev->async) > 0 @@ -1789,7 +1789,7 @@ static unsigned int comedi_poll(struct file *file, poll_table *wait) } } write_subdev = comedi_get_write_subdevice(dev_file_info); - if (write_subdev) { + if (write_subdev && write_subdev->async) { poll_wait(file, &write_subdev->async->wait_head, wait); comedi_buf_write_alloc(write_subdev->async, write_subdev->async->prealloc_bufsz); @@ -1831,7 +1831,7 @@ static ssize_t comedi_write(struct file *file, const char __user *buf, } s = comedi_get_write_subdevice(dev_file_info); - if (s == NULL) { + if (s == NULL || s->async == NULL) { retval = -EIO; goto done; } @@ -1942,7 +1942,7 @@ static ssize_t comedi_read(struct file *file, char __user *buf, size_t nbytes, } s = comedi_get_read_subdevice(dev_file_info); - if (s == NULL) { + if (s == NULL || s->async == NULL) { retval = -EIO; goto done; } |