diff options
| author | Ian Abbott <abbotti@mev.co.uk> | 2013-02-05 12:50:40 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-02-05 11:23:32 -0800 |
| commit | cc400e185c07c15a42d2635995f422de5b94b696 (patch) | |
| tree | 101b8c0466ace7355e678331e2041afdded61908 /drivers | |
| parent | 4a79f730179061c54d5c4ce1b59c1babbb05912f (diff) | |
staging: comedi: check s->async for poll(), read() and write()
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>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 bd89e785fe6..b1e8cdbd1ce 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -1839,7 +1839,7 @@ static unsigned int comedi_poll(struct file *file, poll_table *wait) } s = comedi_read_subdevice(info); - if (s) { + if (s && s->async) { poll_wait(file, &s->async->wait_head, wait); if (!s->busy || !comedi_is_subdevice_running(s) || comedi_buf_read_n_available(s->async) > 0) @@ -1847,7 +1847,7 @@ static unsigned int comedi_poll(struct file *file, poll_table *wait) } s = comedi_write_subdevice(info); - if (s) { + if (s && s->async) { unsigned int bps = bytes_per_sample(s->async->subdevice); poll_wait(file, &s->async->wait_head, wait); @@ -1882,7 +1882,7 @@ static ssize_t comedi_write(struct file *file, const char __user *buf, } s = comedi_write_subdevice(info); - if (!s) + if (!s || !s->async) return -EIO; async = s->async; @@ -1977,7 +1977,7 @@ static ssize_t comedi_read(struct file *file, char __user *buf, size_t nbytes, } s = comedi_read_subdevice(info); - if (!s) + if (!s || !s->async) return -EIO; async = s->async; |