| From b7fb2dad571d1e21173c06cef0bced77b323990a Mon Sep 17 00:00:00 2001 |
| From: Sujit Kautkar <sujitka@chromium.org> |
| Date: Mon, 10 Jan 2022 10:47:36 -0800 |
| Subject: rpmsg: char: Fix race between the release of rpmsg_ctrldev and cdev |
| |
| From: Sujit Kautkar <sujitka@chromium.org> |
| |
| commit b7fb2dad571d1e21173c06cef0bced77b323990a upstream. |
| |
| struct rpmsg_ctrldev contains a struct cdev. The current code frees |
| the rpmsg_ctrldev struct in rpmsg_ctrldev_release_device(), but the |
| cdev is a managed object, therefore its release is not predictable |
| and the rpmsg_ctrldev could be freed before the cdev is entirely |
| released, as in the backtrace below. |
| |
| [ 93.625603] ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x7c |
| [ 93.636115] WARNING: CPU: 0 PID: 12 at lib/debugobjects.c:488 debug_print_object+0x13c/0x1b0 |
| [ 93.644799] Modules linked in: veth xt_cgroup xt_MASQUERADE rfcomm algif_hash algif_skcipher af_alg uinput ip6table_nat fuse uvcvideo videobuf2_vmalloc venus_enc venus_dec videobuf2_dma_contig hci_uart btandroid btqca snd_soc_rt5682_i2c bluetooth qcom_spmi_temp_alarm snd_soc_rt5682v |
| [ 93.715175] CPU: 0 PID: 12 Comm: kworker/0:1 Tainted: G B 5.4.163-lockdep #26 |
| [ 93.723855] Hardware name: Google Lazor (rev3 - 8) with LTE (DT) |
| [ 93.730055] Workqueue: events kobject_delayed_cleanup |
| [ 93.735271] pstate: 60c00009 (nZCv daif +PAN +UAO) |
| [ 93.740216] pc : debug_print_object+0x13c/0x1b0 |
| [ 93.744890] lr : debug_print_object+0x13c/0x1b0 |
| [ 93.749555] sp : ffffffacf5bc7940 |
| [ 93.752978] x29: ffffffacf5bc7940 x28: dfffffd000000000 |
| [ 93.758448] x27: ffffffacdb11a800 x26: dfffffd000000000 |
| [ 93.763916] x25: ffffffd0734f856c x24: dfffffd000000000 |
| [ 93.769389] x23: 0000000000000000 x22: ffffffd0733c35b0 |
| [ 93.774860] x21: ffffffd0751994a0 x20: ffffffd075ec27c0 |
| [ 93.780338] x19: ffffffd075199100 x18: 00000000000276e0 |
| [ 93.785814] x17: 0000000000000000 x16: dfffffd000000000 |
| [ 93.791291] x15: ffffffffffffffff x14: 6e6968207473696c |
| [ 93.796768] x13: 0000000000000000 x12: ffffffd075e2b000 |
| [ 93.802244] x11: 0000000000000001 x10: 0000000000000000 |
| [ 93.807723] x9 : d13400dff1921900 x8 : d13400dff1921900 |
| [ 93.813200] x7 : 0000000000000000 x6 : 0000000000000000 |
| [ 93.818676] x5 : 0000000000000080 x4 : 0000000000000000 |
| [ 93.824152] x3 : ffffffd0732a0fa4 x2 : 0000000000000001 |
| [ 93.829628] x1 : ffffffacf5bc7580 x0 : 0000000000000061 |
| [ 93.835104] Call trace: |
| [ 93.837644] debug_print_object+0x13c/0x1b0 |
| [ 93.841963] __debug_check_no_obj_freed+0x25c/0x3c0 |
| [ 93.846987] debug_check_no_obj_freed+0x18/0x20 |
| [ 93.851669] slab_free_freelist_hook+0xbc/0x1e4 |
| [ 93.856346] kfree+0xfc/0x2f4 |
| [ 93.859416] rpmsg_ctrldev_release_device+0x78/0xb8 |
| [ 93.864445] device_release+0x84/0x168 |
| [ 93.868310] kobject_cleanup+0x12c/0x298 |
| [ 93.872356] kobject_delayed_cleanup+0x10/0x18 |
| [ 93.876948] process_one_work+0x578/0x92c |
| [ 93.881086] worker_thread+0x804/0xcf8 |
| [ 93.884963] kthread+0x2a8/0x314 |
| [ 93.888303] ret_from_fork+0x10/0x18 |
| |
| The cdev_device_add/del() API was created to address this issue (see |
| commit '233ed09d7fda ("chardev: add helper function to register char |
| devs with a struct device")'), use it instead of cdev add/del(). |
| |
| Fixes: c0cdc19f84a4 ("rpmsg: Driver for user space endpoint interface") |
| Signed-off-by: Sujit Kautkar <sujitka@chromium.org> |
| Signed-off-by: Matthias Kaehlcke <mka@chromium.org> |
| Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org> |
| Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> |
| Reviewed-by: Stephen Boyd <swboyd@chromium.org> |
| Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> |
| Link: https://lore.kernel.org/r/20220110104706.v6.1.Iaac908f3e3149a89190ce006ba166e2d3fd247a3@changeid |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| drivers/rpmsg/rpmsg_char.c | 11 ++--------- |
| 1 file changed, 2 insertions(+), 9 deletions(-) |
| |
| --- a/drivers/rpmsg/rpmsg_char.c |
| +++ b/drivers/rpmsg/rpmsg_char.c |
| @@ -461,7 +461,6 @@ static void rpmsg_ctrldev_release_device |
| |
| ida_simple_remove(&rpmsg_ctrl_ida, dev->id); |
| ida_simple_remove(&rpmsg_minor_ida, MINOR(dev->devt)); |
| - cdev_del(&ctrldev->cdev); |
| kfree(ctrldev); |
| } |
| |
| @@ -496,19 +495,13 @@ static int rpmsg_chrdev_probe(struct rpm |
| dev->id = ret; |
| dev_set_name(&ctrldev->dev, "rpmsg_ctrl%d", ret); |
| |
| - ret = cdev_add(&ctrldev->cdev, dev->devt, 1); |
| + ret = cdev_device_add(&ctrldev->cdev, &ctrldev->dev); |
| if (ret) |
| goto free_ctrl_ida; |
| |
| /* We can now rely on the release function for cleanup */ |
| dev->release = rpmsg_ctrldev_release_device; |
| |
| - ret = device_add(dev); |
| - if (ret) { |
| - dev_err(&rpdev->dev, "device_add failed: %d\n", ret); |
| - put_device(dev); |
| - } |
| - |
| dev_set_drvdata(&rpdev->dev, ctrldev); |
| |
| return ret; |
| @@ -534,7 +527,7 @@ static void rpmsg_chrdev_remove(struct r |
| if (ret) |
| dev_warn(&rpdev->dev, "failed to nuke endpoints: %d\n", ret); |
| |
| - device_del(&ctrldev->dev); |
| + cdev_device_del(&ctrldev->cdev, &ctrldev->dev); |
| put_device(&ctrldev->dev); |
| } |
| |
