drivers/rapidio/rio_cm.c: prevent possible heap overwrite

In

riocm_cdev_ioctl(RIO_CM_CHAN_SEND)
   -> cm_chan_msg_send()
      -> riocm_ch_send()

cm_chan_msg_send() checks that userspace didn't send too much data but
riocm_ch_send() failed to check that userspace sent sufficient data.  The
result is that riocm_ch_send() can write to fields in the rio_ch_chan_hdr
which were outside the bounds of the space which cm_chan_msg_send()
allocated.

Address this by teaching riocm_ch_send() to check that the entire
rio_ch_chan_hdr was copied in from userspace.

Reported-by: maher azz <maherazz04@gmail.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Alexandre Bounine <alex.bou9@gmail.com>
Cc: Linus Torvalds <torvalds@linuxfoundation.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/drivers/rapidio/rio_cm.c b/drivers/rapidio/rio_cm.c
index 97287e838ce16a909ace4e59675bb947b39244b4..66464674223fb15502d145eb01245cadc4243d71 100644 (file)
--- a/drivers/rapidio/rio_cm.c
+++ b/drivers/rapidio/rio_cm.c
@@ -783,6 +783,9 @@ static int riocm_ch_send(u16 ch_id, void *buf, int len)
        if (buf == NULL || ch_id == 0 || len == 0 || len > RIO_MAX_MSG_SIZE)
                return -EINVAL;
 
+       if (len < sizeof(struct rio_ch_chan_hdr))
+               return -EINVAL;         /* insufficient data from user */
+
        ch = riocm_get_channel(ch_id);
        if (!ch) {
                riocm_error("%s(%d) ch_%d not found", current->comm,