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Sujit Kautkar 85aba11a8e rpmsg: char: Fix race between the release of rpmsg_ctrldev and cdev commit `b7fb2dad57` 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: `c0cdc19f84` ("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>		2022-02-01 17:27:07 +01:00
arch	powerpc/32: Fix boot failure with GCC latent entropy plugin	2022-02-01 17:27:06 +01:00
block	block: add bio_start_io_acct_time() to control start_time	2022-02-01 17:27:03 +01:00
certs	certs: Add support for using elliptic curve keys for signing modules	2021-08-23 19:55:42 +03:00
crypto	crypto: jitter - consider 32 LSB for APT	2022-01-27 11:04:31 +01:00
Documentation	psi: Fix uaf issue when psi trigger is destroyed while being polled	2022-02-01 17:27:01 +01:00
drivers	rpmsg: char: Fix race between the release of rpmsg_ctrldev and cdev	2022-02-01 17:27:07 +01:00
fs	ocfs2: fix a deadlock when commit trans	2022-02-01 17:27:05 +01:00
include	usb: roles: fix include/linux/usb/role.h compile issue	2022-02-01 17:27:07 +01:00
init	init: make unknown command line param message clearer	2021-11-18 19:17:11 +01:00
ipc	shm: extend forced shm destroy to support objects from several IPC nses	2021-11-25 09:48:42 +01:00
kernel	sched/membarrier: Fix membarrier-rseq fence command missing from query bitmask	2022-02-01 17:27:05 +01:00
lib	lib/test_meminit: destroy cache in kmem_cache_alloc_bulk() test	2022-01-27 11:05:44 +01:00
LICENSES	LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes"	2021-07-15 06:31:24 -06:00
mm	memcg: better bounds on the memcg stats updates	2022-01-29 10:58:24 +01:00
net	fsnotify: fix fsnotify hooks in pseudo filesystems	2022-02-01 17:27:01 +01:00
samples	samples: bpf: Fix 'unknown warning group' build warning on Clang	2022-01-27 11:03:29 +01:00
scripts	scripts: sphinx-pre-install: Fix ctex support on Debian	2022-01-27 11:05:44 +01:00
security	selinux: fix potential memleak in selinux_add_opt()	2022-01-27 11:03:43 +01:00
sound	ASoC: mediatek: mt8183: fix device_node leak	2022-01-27 11:05:04 +01:00
tools	mm/hmm.c: allow VM_MIXEDMAP to work with hmm_range_fault	2022-01-27 11:05:43 +01:00
usr	kbuild: remove include/linux/cyclades.h from header file check	2022-02-01 17:27:04 +01:00
virt	Revert "KVM: SVM: avoid infinite loop on NPF from bad address"	2022-02-01 17:27:01 +01:00
.clang-format	clang-format: Update with the latest for_each macro list	2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore	Opt out of scripts/get_maintainer.pl	2019-05-16 10:53:40 -07:00
.gitattributes	.gitattributes: use 'dts' diff driver for dts files	2019-12-04 19:44:11 -08:00
.gitignore	.gitignore: ignore only top-level modules.builtin	2021-05-02 00:43:35 +09:00
.mailmap	mailmap: add Andrej Shadura	2021-10-18 20:22:03 -10:00
COPYING	COPYING: state that all contributions really are covered by this file	2020-02-10 13:32:20 -08:00
CREDITS	MAINTAINERS: Move Daniel Drake to credits	2021-09-21 08:34:58 +03:00
Kbuild	kbuild: rename hostprogs-y/always to hostprogs/always-y	2020-02-04 01:53:07 +09:00
Kconfig	kbuild: ensure full rebuild when the compiler is updated	2020-05-12 13:28:33 +09:00
MAINTAINERS	drm fixes for 5.15 final	2021-10-28 12:17:01 -07:00
Makefile	Linux 5.15.18	2022-01-29 10:58:25 +01:00
README	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.