On 13/03/2023 14:45, Zheng Hacker wrote: > Hans Verkuil <hverkuil@xxxxxxxxx> 于2023年3月13日周一 21:17写道： >> >> On 07/03/2023 16:35, Zheng Wang wrote: >>> In hantro_probe, vpu->watchdog_work is bound with >>> hantro_watchdog. Then hantro_end_prepare_run may >>> be called to start the work. >>> >>> If we close the file or remove the module which will >>> call hantro_release and hantro_remove to make cleanup, >>> there may be a unfinished work. The possible sequence >>> is as follows, which will cause a typical UAF bug. >>> >>> The same thing will happen in hantro_release, and use >>> ctx after freeing it. >>> >>> Fix it by canceling the work before cleanup in hantro_release. >>> >>> CPU0 CPU1 >>> >>> |hantro_watchdog >>> hantro_remove | >>> v4l2_m2m_release | >>> kfree(m2m_dev); | >>> | >>> | v4l2_m2m_get_curr_priv >>> | m2m_dev->curr_ctx //use >>> >>> Signed-off-by: Zheng Wang <zyytlz.wz@xxxxxxx> >>> --- >>> drivers/media/platform/verisilicon/hantro_drv.c | 1 + >>> 1 file changed, 1 insertion(+) >>> >>> diff --git a/drivers/media/platform/verisilicon/hantro_drv.c b/drivers/media/platform/verisilicon/hantro_drv.c >>> index b0aeedae7b65..cf00ccaa7829 100644 >>> --- a/drivers/media/platform/verisilicon/hantro_drv.c >>> +++ b/drivers/media/platform/verisilicon/hantro_drv.c >>> @@ -601,6 +601,7 @@ static int hantro_release(struct file *filp) >>> * No need for extra locking because this was the last reference >>> * to this file. >>> */ >>> + cancel_delayed_work(&vpu->watchdog_work); >>> v4l2_m2m_ctx_release(ctx->fh.m2m_ctx); >>> v4l2_fh_del(&ctx->fh); >>> v4l2_fh_exit(&ctx->fh); >> >> drivers/media/platform/verisilicon/hantro_drv.c: In function ‘hantro_release’: >> drivers/media/platform/verisilicon/hantro_drv.c:604:30: error: ‘vpu’ undeclared (first use in this function); did you mean ‘fpu’? >> 604 | cancel_delayed_work(&vpu->watchdog_work); >> | ^~~ >> | fpu >> drivers/media/platform/verisilicon/hantro_drv.c:604:30: note: each undeclared identifier is reported only once for each function it appears in >> >> You clearly didn't compile this patch! >> > Sorry for my mistake. I was hurried to report the issue and discuss > with developer to confirm it . I'll complete it and test it locally. Was this UAF actually observed, or is it theoretical? Regards, Hans > > Best regards, > Zheng
