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.Iaac908f3e3149a89190ce006ba166... 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 @@ -455,7 +455,6 @@ 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); }
@@ -490,19 +489,13 @@ 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; @@ -528,7 +521,7 @@ 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); }