[PATCH v3 1/4] media: imx8-isi: fix use-after-free on remove

[Xiaolei Wang]

KASAN reports a slab-use-after-free in __media_entity_remove_link()
during rmmod of imx8_isi:

  BUG: KASAN: slab-use-after-free in __media_entity_remove_link+0x608/0x650
  Read of size 2 at addr ffff0000d47cb02a by task rmmod/724

  Call trace:
   __media_entity_remove_link+0x608/0x650
   __media_entity_remove_links+0x78/0x144
   __media_device_unregister_entity+0x150/0x280
   media_device_unregister_entity+0x48/0x68
   v4l2_device_unregister_subdev+0x158/0x300
   v4l2_async_unbind_subdev_one+0x22c/0x358
   v4l2_async_nf_unbind_all_subdevs+0xfc/0x1c0
   v4l2_async_nf_unregister+0x5c/0x14c
   mxc_isi_remove+0x124/0x2a0 [imx8_isi]

  Allocated by task 249:
   __kmalloc_noprof+0x27c/0x690
   mxc_isi_crossbar_init+0x22c/0x560 [imx8_isi]

  Freed by task 724:
   kfree+0x1e4/0x5b0
   mxc_isi_crossbar_cleanup+0x34/0x80 [imx8_isi]
   mxc_isi_remove+0x11c/0x2a0 [imx8_isi]

The problem is that mxc_isi_remove() calls mxc_isi_crossbar_cleanup()
before mxc_isi_v4l2_cleanup(). The crossbar cleanup frees the media
entity pads, but the subsequent v4l2 cleanup still tries to remove
media links that reference those pads.

Fix this by calling mxc_isi_v4l2_cleanup() before
mxc_isi_crossbar_cleanup() to ensure all media entities are properly
unregistered while the pads are still valid.

Fixes: cf21f328fcaf ("media: nxp: Add i.MX8 ISI driver")
Signed-off-by: Xiaolei Wang <xiaolei.wang@xxxxxxxxxxxxx>
Reviewed-by: Frank Li <Frank.Li@xxxxxxx>
Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
---
 drivers/media/platform/nxp/imx8-isi/imx8-isi-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/platform/nxp/imx8-isi/imx8-isi-core.c b/drivers/media/platform/nxp/imx8-isi/imx8-isi-core.c
index 4bf8570e1b9e..2d639b789910 100644
--- a/drivers/media/platform/nxp/imx8-isi/imx8-isi-core.c
+++ b/drivers/media/platform/nxp/imx8-isi/imx8-isi-core.c
@@ -556,8 +556,8 @@ static void mxc_isi_remove(struct platform_device *pdev)
 		mxc_isi_pipe_cleanup(pipe);
 	}
 
-	mxc_isi_crossbar_cleanup(&isi->crossbar);
 	mxc_isi_v4l2_cleanup(isi);
+	mxc_isi_crossbar_cleanup(&isi->crossbar);
 }
 
 static const struct of_device_id mxc_isi_of_match[] = {
-- 
2.43.0