| Message ID | 20230307153542.1178065-1-zyytlz.wz@163.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | media: hantro: fix use after free bug in hantro_release due to race condition | expand |
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@163.com> > --- > 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! Regards, Hans
Hans Verkuil <hverkuil@xs4all.nl> 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@163.com> > > --- > > 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. Best regards, Zheng
On 13/03/2023 14:45, Zheng Hacker wrote: > Hans Verkuil <hverkuil@xs4all.nl> 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@163.com> >>> --- >>> 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
Hans Verkuil <hverkuil@xs4all.nl> 于2023年3月13日周一 21:47写道： > > On 13/03/2023 14:45, Zheng Hacker wrote: > > Hans Verkuil <hverkuil@xs4all.nl> 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@163.com> > >>> --- > >>> 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? > This is a bug identified during a static audit and referenced to other similar issues. There's no PoC but some work has proven that the race time window can be enlarge which make the UAF practical. Best regards, Zheng
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);
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@163.com> --- drivers/media/platform/verisilicon/hantro_drv.c | 1 + 1 file changed, 1 insertion(+)