diff options
| author | Ian Abbott <abbotti@mev.co.uk> | 2013-02-27 10:56:19 +0000 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2013-03-06 03:23:50 +0000 |
| commit | 1ff13c78ca3975a94460a6a0b49acf9a787ed350 (patch) | |
| tree | d889e1d1ba4ec5a710e768956f1d7c35b895882d /drivers | |
| parent | 35ad1797ad99b8e73758c805803021cbda799dcb (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: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'drivers')
| -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 13e79a1110fa..a023f522408d 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -1574,7 +1574,7 @@ 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 @@ -1584,7 +1584,7 @@ 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); @@ -1626,7 +1626,7 @@ 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; } @@ -1737,7 +1737,7 @@ 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; } |