Merge tag 'char-misc-4.6-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc

Pull misc driver fixes from Gfreg KH:
 "Here are three small fixes for some driver problems that were
  reported.  Full details in the shortlog below.

  All of these have been in linux-next with no reported issues"

* tag 'char-misc-4.6-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  nvmem: mxs-ocotp: fix buffer overflow in read
  Drivers: hv: vmbus: Fix signaling logic in hv_need_to_signal_on_read()
  misc: mic: Fix for double fetch security bug in VOP driver

3 files changed, 27 insertions, 8 deletions

diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 5613e2b5cff7..a40a73a7b71d 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -103,15 +103,29 @@ static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi)
  *    there is room for the producer to send the pending packet.
  */
 
-static bool hv_need_to_signal_on_read(u32 prev_write_sz,
-                                      struct hv_ring_buffer_info *rbi)
+static bool hv_need_to_signal_on_read(struct hv_ring_buffer_info *rbi)
 {
         u32 cur_write_sz;
         u32 r_size;
-        u32 write_loc = rbi->ring_buffer->write_index;
+        u32 write_loc;
         u32 read_loc = rbi->ring_buffer->read_index;
-        u32 pending_sz = rbi->ring_buffer->pending_send_sz;
+        u32 pending_sz;
 
+        /*
+         * Issue a full memory barrier before making the signaling decision.
+         * Here is the reason for having this barrier:
+         * If the reading of the pend_sz (in this function)
+         * were to be reordered and read before we commit the new read
+         * index (in the calling function)  we could
+         * have a problem. If the host were to set the pending_sz after we
+         * have sampled pending_sz and go to sleep before we commit the
+         * read index, we could miss sending the interrupt. Issue a full
+         * memory barrier to address this.
+         */
+        mb();
+
+        pending_sz = rbi->ring_buffer->pending_send_sz;
+        write_loc = rbi->ring_buffer->write_index;
         /* If the other end is not blocked on write don't bother. */
         if (pending_sz == 0)
                 return false;
@@ -120,7 +134,7 @@ static bool hv_need_to_signal_on_read(u32 prev_write_sz,
         cur_write_sz = write_loc >= read_loc ? r_size - (write_loc - read_loc) :
                         read_loc - write_loc;
 
-        if ((prev_write_sz < pending_sz) && (cur_write_sz >= pending_sz))
+        if (cur_write_sz >= pending_sz)
                 return true;
 
         return false;
@@ -455,7 +469,7 @@ int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info,
         /* Update the read index */
         hv_set_next_read_location(inring_info, next_read_location);
 
-        *signal = hv_need_to_signal_on_read(bytes_avail_towrite, inring_info);
+        *signal = hv_need_to_signal_on_read(inring_info);
 
         return ret;
 }
diff --git a/drivers/misc/mic/vop/vop_vringh.c b/drivers/misc/mic/vop/vop_vringh.c
index e94c7fb6712a..88e45234d527 100644
--- a/drivers/misc/mic/vop/vop_vringh.c
+++ b/drivers/misc/mic/vop/vop_vringh.c
@@ -945,6 +945,11 @@ static long vop_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
                         ret = -EFAULT;
                         goto free_ret;
                 }
+                /* Ensure desc has not changed between the two reads */
+                if (memcmp(&dd, dd_config, sizeof(dd))) {
+                        ret = -EINVAL;
+                        goto free_ret;
+                }
                 mutex_lock(&vdev->vdev_mutex);
                 mutex_lock(&vi->vop_mutex);
                 ret = vop_virtio_add_device(vdev, dd_config);
diff --git a/drivers/nvmem/mxs-ocotp.c b/drivers/nvmem/mxs-ocotp.c
index 8ba19bba3156..2bb3c5799ac4 100644
--- a/drivers/nvmem/mxs-ocotp.c
+++ b/drivers/nvmem/mxs-ocotp.c
@@ -94,7 +94,7 @@ static int mxs_ocotp_read(void *context, const void *reg, size_t reg_size,
         if (ret)
                 goto close_banks;
 
-        while (val_size) {
+        while (val_size >= reg_size) {
                 if ((offset < OCOTP_DATA_OFFSET) || (offset % 16)) {
                         /* fill up non-data register */
                         *buf = 0;
@@ -103,7 +103,7 @@ static int mxs_ocotp_read(void *context, const void *reg, size_t reg_size,
                 }
 
                 buf++;
-                val_size--;
+                val_size -= reg_size;
                 offset += reg_size;
         }