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fbdev: smscufx: Fix several use-after-free bugs
commit cc67482c9e
upstream.
Several types of UAFs can occur when physically removing a USB device.
Adds ufx_ops_destroy() function to .fb_destroy of fb_ops, and
in this function, there is kref_put() that finally calls ufx_free().
This fix prevents multiple UAFs.
Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com>
Link: https://lore.kernel.org/linux-fbdev/20221011153436.GA4446@ubuntu/
Cc: <stable@vger.kernel.org>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
31d019f2a4
commit
8d924b262f
1 changed files with 31 additions and 26 deletions
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@ -97,7 +97,6 @@ struct ufx_data {
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struct kref kref;
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int fb_count;
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bool virtualized; /* true when physical usb device not present */
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struct delayed_work free_framebuffer_work;
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atomic_t usb_active; /* 0 = update virtual buffer, but no usb traffic */
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atomic_t lost_pixels; /* 1 = a render op failed. Need screen refresh */
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u8 *edid; /* null until we read edid from hw or get from sysfs */
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@ -1117,15 +1116,24 @@ static void ufx_free(struct kref *kref)
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{
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struct ufx_data *dev = container_of(kref, struct ufx_data, kref);
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/* this function will wait for all in-flight urbs to complete */
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if (dev->urbs.count > 0)
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ufx_free_urb_list(dev);
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pr_debug("freeing ufx_data %p", dev);
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kfree(dev);
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}
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static void ufx_ops_destory(struct fb_info *info)
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{
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struct ufx_data *dev = info->par;
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int node = info->node;
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/* Assume info structure is freed after this point */
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framebuffer_release(info);
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pr_debug("fb_info for /dev/fb%d has been freed", node);
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/* release reference taken by kref_init in probe() */
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kref_put(&dev->kref, ufx_free);
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}
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static void ufx_release_urb_work(struct work_struct *work)
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{
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struct urb_node *unode = container_of(work, struct urb_node,
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@ -1134,14 +1142,9 @@ static void ufx_release_urb_work(struct work_struct *work)
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up(&unode->dev->urbs.limit_sem);
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}
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static void ufx_free_framebuffer_work(struct work_struct *work)
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static void ufx_free_framebuffer(struct ufx_data *dev)
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{
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struct ufx_data *dev = container_of(work, struct ufx_data,
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free_framebuffer_work.work);
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struct fb_info *info = dev->info;
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int node = info->node;
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unregister_framebuffer(info);
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if (info->cmap.len != 0)
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fb_dealloc_cmap(&info->cmap);
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@ -1153,11 +1156,6 @@ static void ufx_free_framebuffer_work(struct work_struct *work)
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dev->info = NULL;
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/* Assume info structure is freed after this point */
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framebuffer_release(info);
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pr_debug("fb_info for /dev/fb%d has been freed", node);
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/* ref taken in probe() as part of registering framebfufer */
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kref_put(&dev->kref, ufx_free);
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}
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@ -1169,11 +1167,13 @@ static int ufx_ops_release(struct fb_info *info, int user)
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{
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struct ufx_data *dev = info->par;
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mutex_lock(&disconnect_mutex);
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dev->fb_count--;
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/* We can't free fb_info here - fbmem will touch it when we return */
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if (dev->virtualized && (dev->fb_count == 0))
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schedule_delayed_work(&dev->free_framebuffer_work, HZ);
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ufx_free_framebuffer(dev);
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if ((dev->fb_count == 0) && (info->fbdefio)) {
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fb_deferred_io_cleanup(info);
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@ -1186,6 +1186,8 @@ static int ufx_ops_release(struct fb_info *info, int user)
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kref_put(&dev->kref, ufx_free);
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mutex_unlock(&disconnect_mutex);
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return 0;
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}
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@ -1292,6 +1294,7 @@ static const struct fb_ops ufx_ops = {
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.fb_blank = ufx_ops_blank,
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.fb_check_var = ufx_ops_check_var,
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.fb_set_par = ufx_ops_set_par,
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.fb_destroy = ufx_ops_destory,
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};
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/* Assumes &info->lock held by caller
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@ -1673,9 +1676,6 @@ static int ufx_usb_probe(struct usb_interface *interface,
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goto destroy_modedb;
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}
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INIT_DELAYED_WORK(&dev->free_framebuffer_work,
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ufx_free_framebuffer_work);
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retval = ufx_reg_read(dev, 0x3000, &id_rev);
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check_warn_goto_error(retval, "error %d reading 0x3000 register from device", retval);
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dev_dbg(dev->gdev, "ID_REV register value 0x%08x", id_rev);
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@ -1748,10 +1748,12 @@ static int ufx_usb_probe(struct usb_interface *interface,
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static void ufx_usb_disconnect(struct usb_interface *interface)
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{
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struct ufx_data *dev;
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struct fb_info *info;
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mutex_lock(&disconnect_mutex);
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dev = usb_get_intfdata(interface);
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info = dev->info;
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pr_debug("USB disconnect starting\n");
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@ -1765,12 +1767,15 @@ static void ufx_usb_disconnect(struct usb_interface *interface)
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/* if clients still have us open, will be freed on last close */
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if (dev->fb_count == 0)
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schedule_delayed_work(&dev->free_framebuffer_work, 0);
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ufx_free_framebuffer(dev);
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/* release reference taken by kref_init in probe() */
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kref_put(&dev->kref, ufx_free);
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/* this function will wait for all in-flight urbs to complete */
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if (dev->urbs.count > 0)
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ufx_free_urb_list(dev);
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/* consider ufx_data freed */
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pr_debug("freeing ufx_data %p", dev);
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unregister_framebuffer(info);
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mutex_unlock(&disconnect_mutex);
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}
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