lkml.org 
[lkml]   [2013]   [Mar]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[ 029/153] staging: comedi: check s->async for poll(), read() and write()
    3.2-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Ian Abbott <abbotti@mev.co.uk>

    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>
    ---
    drivers/staging/comedi/comedi_fops.c | 8 ++++----
    1 file changed, 4 insertions(+), 4 deletions(-)

    --- a/drivers/staging/comedi/comedi_fops.c
    +++ b/drivers/staging/comedi/comedi_fops.c
    @@ -1574,7 +1574,7 @@ static unsigned int comedi_poll(struct f

    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 f
    }
    }
    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
    }

    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 *
    }

    s = comedi_get_read_subdevice(dev_file_info);
    - if (s == NULL) {
    + if (s == NULL || s->async == NULL) {
    retval = -EIO;
    goto done;
    }



    \
     
     \ /
      Last update: 2013-03-04 05:41    [W:2.246 / U:0.228 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site