| Message ID | 20211102165137.v3.1.I2858f54e737295d746ea67e1dc0068fe63913ae5@changeid (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | Fix two kernel warnings in glink driver | expand |
Hi Sujit, On Tue, Nov 02, 2021 at 04:51:49PM -0700, Sujit Kautkar wrote: > qcom_glink_rpdev_release() sets channel->rpdev to NULL. However, with > debug enabled kernel, qcom_glink_rpdev_release() gets delayed due to > delayed kobject release and channel gets released by that time and > triggers below kernel warning. To avoid this use-after-free, clear ept > pointers during ept destroy and channel release and add a new condition > in qcom_glink_rpdev_release() to access channel > > | BUG: KASAN: use-after-free in qcom_glink_rpdev_release+0x54/0x70 > | Write of size 8 at addr ffffffaba438e8d0 by task kworker/6:1/54 > | > | CPU: 6 PID: 54 Comm: kworker/6:1 Not tainted 5.4.109-lockdep #16 > | Hardware name: Google Lazor (rev3+) with KB Backlight (DT) > | Workqueue: events kobject_delayed_cleanup > | Call trace: > | dump_backtrace+0x0/0x284 > | show_stack+0x20/0x2c > | dump_stack+0xd4/0x170 > | print_address_description+0x3c/0x4a8 > | __kasan_report+0x144/0x168 > | kasan_report+0x10/0x18 > | __asan_report_store8_noabort+0x1c/0x24 > | qcom_glink_rpdev_release+0x54/0x70 > | device_release+0x68/0x14c > | kobject_delayed_cleanup+0x158/0x2cc > | process_one_work+0x7cc/0x10a4 > | worker_thread+0x80c/0xcec > | kthread+0x2a8/0x314 > | ret_from_fork+0x10/0x18 > > Signed-off-by: Sujit Kautkar <sujitka@chromium.org> > --- > Changes in v3: > - Clear ept pointers and add extra conditions > > Changes in v2: > - Fix typo in commit message > > drivers/rpmsg/qcom_glink_native.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c > index e1444fefdd1c0..0c64a6f7a4f09 100644 > --- a/drivers/rpmsg/qcom_glink_native.c > +++ b/drivers/rpmsg/qcom_glink_native.c > @@ -269,6 +269,9 @@ static void qcom_glink_channel_release(struct kref *ref) > idr_destroy(&channel->riids); > spin_unlock_irqrestore(&channel->intent_lock, flags); > > + if (channel->rpdev) > + channel->rpdev->ept = NULL; > + > kfree(channel->name); > kfree(channel); > } > @@ -1214,6 +1217,8 @@ static void qcom_glink_destroy_ept(struct rpmsg_endpoint *ept) > channel->ept.cb = NULL; > spin_unlock_irqrestore(&channel->recv_lock, flags); > > + channel->rpdev->ept = NULL; > + > /* Decouple the potential rpdev from the channel */ > channel->rpdev = NULL; > > @@ -1371,9 +1376,12 @@ static const struct rpmsg_endpoint_ops glink_endpoint_ops = { > static void qcom_glink_rpdev_release(struct device *dev) > { > struct rpmsg_device *rpdev = to_rpmsg_device(dev); > - struct glink_channel *channel = to_glink_channel(rpdev->ept); > + struct glink_channel *channel = NULL; no need to initialize the pointer, it is assigned in the path that uses it. > > - channel->rpdev = NULL; > + if (rpdev->ept) { > + channel = to_glink_channel(rpdev->ept); > + channel->rpdev = NULL; > + } > kfree(rpdev); > } Looks like this is already fixed in -next by: commit 343ba27b6f9d473ec3e602cc648300eb03a7fa05 Author: Chris Lew <clew@codeaurora.org> Date: Thu Jul 30 10:48:15 2020 +0530 rpmsg: glink: Remove channel decouple from rpdev release If a channel is being rapidly restarting and the kobj release worker is busy, there is a chance the rpdev_release function will run after the channel struct itself has been released. There should not be a need to decouple the channel from rpdev in the rpdev release since that should only happen from the close commands. Signed-off-by: Chris Lew <clew@codeaurora.org> Signed-off-by: Deepak Kumar Singh <deesin@codeaurora.org> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> Link: https://lore.kernel.org/r/1596086296-28529-6-git-send-email-deesin@codeaurora.org
diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c index e1444fefdd1c0..0c64a6f7a4f09 100644 --- a/drivers/rpmsg/qcom_glink_native.c +++ b/drivers/rpmsg/qcom_glink_native.c @@ -269,6 +269,9 @@ static void qcom_glink_channel_release(struct kref *ref) idr_destroy(&channel->riids); spin_unlock_irqrestore(&channel->intent_lock, flags); + if (channel->rpdev) + channel->rpdev->ept = NULL; + kfree(channel->name); kfree(channel); } @@ -1214,6 +1217,8 @@ static void qcom_glink_destroy_ept(struct rpmsg_endpoint *ept) channel->ept.cb = NULL; spin_unlock_irqrestore(&channel->recv_lock, flags); + channel->rpdev->ept = NULL; + /* Decouple the potential rpdev from the channel */ channel->rpdev = NULL; @@ -1371,9 +1376,12 @@ static const struct rpmsg_endpoint_ops glink_endpoint_ops = { static void qcom_glink_rpdev_release(struct device *dev) { struct rpmsg_device *rpdev = to_rpmsg_device(dev); - struct glink_channel *channel = to_glink_channel(rpdev->ept); + struct glink_channel *channel = NULL; - channel->rpdev = NULL; + if (rpdev->ept) { + channel = to_glink_channel(rpdev->ept); + channel->rpdev = NULL; + } kfree(rpdev); }
qcom_glink_rpdev_release() sets channel->rpdev to NULL. However, with debug enabled kernel, qcom_glink_rpdev_release() gets delayed due to delayed kobject release and channel gets released by that time and triggers below kernel warning. To avoid this use-after-free, clear ept pointers during ept destroy and channel release and add a new condition in qcom_glink_rpdev_release() to access channel | BUG: KASAN: use-after-free in qcom_glink_rpdev_release+0x54/0x70 | Write of size 8 at addr ffffffaba438e8d0 by task kworker/6:1/54 | | CPU: 6 PID: 54 Comm: kworker/6:1 Not tainted 5.4.109-lockdep #16 | Hardware name: Google Lazor (rev3+) with KB Backlight (DT) | Workqueue: events kobject_delayed_cleanup | Call trace: | dump_backtrace+0x0/0x284 | show_stack+0x20/0x2c | dump_stack+0xd4/0x170 | print_address_description+0x3c/0x4a8 | __kasan_report+0x144/0x168 | kasan_report+0x10/0x18 | __asan_report_store8_noabort+0x1c/0x24 | qcom_glink_rpdev_release+0x54/0x70 | device_release+0x68/0x14c | kobject_delayed_cleanup+0x158/0x2cc | process_one_work+0x7cc/0x10a4 | worker_thread+0x80c/0xcec | kthread+0x2a8/0x314 | ret_from_fork+0x10/0x18 Signed-off-by: Sujit Kautkar <sujitka@chromium.org> --- Changes in v3: - Clear ept pointers and add extra conditions Changes in v2: - Fix typo in commit message drivers/rpmsg/qcom_glink_native.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)