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Mauro Carvalho Chehab b1cb7372fa dvb_frontend: don't use-after-free the frontend struct 
dvb_frontend_invoke_release() may free the frontend struct.
So, the free logic can't update it anymore after calling it.

That's OK, as __dvb_frontend_free() is called only when the
krefs are zeroed, so nobody is using it anymore.

That should fix the following KASAN error:

The KASAN report looks like this (running on kernel 3e0cc09a3a (4.14-rc5+)):
==================================================================
BUG: KASAN: use-after-free in __dvb_frontend_free+0x113/0x120
Write of size 8 at addr ffff880067d45a00 by task kworker/0:1/24

CPU: 0 PID: 24 Comm: kworker/0:1 Not tainted 4.14.0-rc5-43687-g06ab8a23e0e6 #545
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
 __dump_stack lib/dump_stack.c:16
 dump_stack+0x292/0x395 lib/dump_stack.c:52
 print_address_description+0x78/0x280 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351
 kasan_report+0x23d/0x350 mm/kasan/report.c:409
 __asan_report_store8_noabort+0x1c/0x20 mm/kasan/report.c:435
 __dvb_frontend_free+0x113/0x120 drivers/media/dvb-core/dvb_frontend.c:156
 dvb_frontend_put+0x59/0x70 drivers/media/dvb-core/dvb_frontend.c:176
 dvb_frontend_detach+0x120/0x150 drivers/media/dvb-core/dvb_frontend.c:2803
 dvb_usb_adapter_frontend_exit+0xd6/0x160 drivers/media/usb/dvb-usb/dvb-usb-dvb.c:340
 dvb_usb_adapter_exit drivers/media/usb/dvb-usb/dvb-usb-init.c:116
 dvb_usb_exit+0x9b/0x200 drivers/media/usb/dvb-usb/dvb-usb-init.c:132
 dvb_usb_device_exit+0xa5/0xf0 drivers/media/usb/dvb-usb/dvb-usb-init.c:295
 usb_unbind_interface+0x21c/0xa90 drivers/usb/core/driver.c:423
 __device_release_driver drivers/base/dd.c:861
 device_release_driver_internal+0x4f1/0x5c0 drivers/base/dd.c:893
 device_release_driver+0x1e/0x30 drivers/base/dd.c:918
 bus_remove_device+0x2f4/0x4b0 drivers/base/bus.c:565
 device_del+0x5c4/0xab0 drivers/base/core.c:1985
 usb_disable_device+0x1e9/0x680 drivers/usb/core/message.c:1170
 usb_disconnect+0x260/0x7a0 drivers/usb/core/hub.c:2124
 hub_port_connect drivers/usb/core/hub.c:4754
 hub_port_connect_change drivers/usb/core/hub.c:5009
 port_event drivers/usb/core/hub.c:5115
 hub_event+0x1318/0x3740 drivers/usb/core/hub.c:5195
 process_one_work+0xc73/0x1d90 kernel/workqueue.c:2119
 worker_thread+0x221/0x1850 kernel/workqueue.c:2253
 kthread+0x363/0x440 kernel/kthread.c:231
 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431

Allocated by task 24:
 save_stack_trace+0x1b/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
 kmem_cache_alloc_trace+0x11e/0x2d0 mm/slub.c:2772
 kmalloc ./include/linux/slab.h:493
 kzalloc ./include/linux/slab.h:666
 dtt200u_fe_attach+0x4c/0x110 drivers/media/usb/dvb-usb/dtt200u-fe.c:212
 dtt200u_frontend_attach+0x35/0x80 drivers/media/usb/dvb-usb/dtt200u.c:136
 dvb_usb_adapter_frontend_init+0x32b/0x660 drivers/media/usb/dvb-usb/dvb-usb-dvb.c:286
 dvb_usb_adapter_init drivers/media/usb/dvb-usb/dvb-usb-init.c:86
 dvb_usb_init drivers/media/usb/dvb-usb/dvb-usb-init.c:162
 dvb_usb_device_init+0xf73/0x17f0 drivers/media/usb/dvb-usb/dvb-usb-init.c:277
 dtt200u_usb_probe+0xa1/0xe0 drivers/media/usb/dvb-usb/dtt200u.c:155
 usb_probe_interface+0x35d/0x8e0 drivers/usb/core/driver.c:361
 really_probe drivers/base/dd.c:413
 driver_probe_device+0x610/0xa00 drivers/base/dd.c:557
 __device_attach_driver+0x230/0x290 drivers/base/dd.c:653
 bus_for_each_drv+0x161/0x210 drivers/base/bus.c:463
 __device_attach+0x26b/0x3c0 drivers/base/dd.c:710
 device_initial_probe+0x1f/0x30 drivers/base/dd.c:757
 bus_probe_device+0x1eb/0x290 drivers/base/bus.c:523
 device_add+0xd0b/0x1660 drivers/base/core.c:1835
 usb_set_configuration+0x104e/0x1870 drivers/usb/core/message.c:1932
 generic_probe+0x73/0xe0 drivers/usb/core/generic.c:174
 usb_probe_device+0xaf/0xe0 drivers/usb/core/driver.c:266
 really_probe drivers/base/dd.c:413
 driver_probe_device+0x610/0xa00 drivers/base/dd.c:557
 __device_attach_driver+0x230/0x290 drivers/base/dd.c:653
 bus_for_each_drv+0x161/0x210 drivers/base/bus.c:463
 __device_attach+0x26b/0x3c0 drivers/base/dd.c:710
 device_initial_probe+0x1f/0x30 drivers/base/dd.c:757
 bus_probe_device+0x1eb/0x290 drivers/base/bus.c:523
 device_add+0xd0b/0x1660 drivers/base/core.c:1835
 usb_new_device+0x7b8/0x1020 drivers/usb/core/hub.c:2457
 hub_port_connect drivers/usb/core/hub.c:4903
 hub_port_connect_change drivers/usb/core/hub.c:5009
 port_event drivers/usb/core/hub.c:5115
 hub_event+0x194d/0x3740 drivers/usb/core/hub.c:5195
 process_one_work+0xc73/0x1d90 kernel/workqueue.c:2119
 worker_thread+0x221/0x1850 kernel/workqueue.c:2253
 kthread+0x363/0x440 kernel/kthread.c:231
 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431

Freed by task 24:
 save_stack_trace+0x1b/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459
 kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:524
 slab_free_hook mm/slub.c:1390
 slab_free_freelist_hook mm/slub.c:1412
 slab_free mm/slub.c:2988
 kfree+0xf6/0x2f0 mm/slub.c:3919
 dtt200u_fe_release+0x3c/0x50 drivers/media/usb/dvb-usb/dtt200u-fe.c:202
 dvb_frontend_invoke_release.part.13+0x1c/0x30 drivers/media/dvb-core/dvb_frontend.c:2790
 dvb_frontend_invoke_release drivers/media/dvb-core/dvb_frontend.c:2789
 __dvb_frontend_free+0xad/0x120 drivers/media/dvb-core/dvb_frontend.c:153
 dvb_frontend_put+0x59/0x70 drivers/media/dvb-core/dvb_frontend.c:176
 dvb_frontend_detach+0x120/0x150 drivers/media/dvb-core/dvb_frontend.c:2803
 dvb_usb_adapter_frontend_exit+0xd6/0x160 drivers/media/usb/dvb-usb/dvb-usb-dvb.c:340
 dvb_usb_adapter_exit drivers/media/usb/dvb-usb/dvb-usb-init.c:116
 dvb_usb_exit+0x9b/0x200 drivers/media/usb/dvb-usb/dvb-usb-init.c:132
 dvb_usb_device_exit+0xa5/0xf0 drivers/media/usb/dvb-usb/dvb-usb-init.c:295
 usb_unbind_interface+0x21c/0xa90 drivers/usb/core/driver.c:423
 __device_release_driver drivers/base/dd.c:861
 device_release_driver_internal+0x4f1/0x5c0 drivers/base/dd.c:893
 device_release_driver+0x1e/0x30 drivers/base/dd.c:918
 bus_remove_device+0x2f4/0x4b0 drivers/base/bus.c:565
 device_del+0x5c4/0xab0 drivers/base/core.c:1985
 usb_disable_device+0x1e9/0x680 drivers/usb/core/message.c:1170
 usb_disconnect+0x260/0x7a0 drivers/usb/core/hub.c:2124
 hub_port_connect drivers/usb/core/hub.c:4754
 hub_port_connect_change drivers/usb/core/hub.c:5009
 port_event drivers/usb/core/hub.c:5115
 hub_event+0x1318/0x3740 drivers/usb/core/hub.c:5195
 process_one_work+0xc73/0x1d90 kernel/workqueue.c:2119
 worker_thread+0x221/0x1850 kernel/workqueue.c:2253
 kthread+0x363/0x440 kernel/kthread.c:231
 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431

The buggy address belongs to the object at ffff880067d45500
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 1280 bytes inside of
 2048-byte region [ffff880067d45500, ffff880067d45d00)
The buggy address belongs to the page:
page:ffffea00019f5000 count:1 mapcount:0 mapping:          (null)
index:0x0 compound_mapcount: 0
flags: 0x100000000008100(slab|head)
raw: 0100000000008100 0000000000000000 0000000000000000 00000001000f000f
raw: dead000000000100 dead000000000200 ffff88006c002d80 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff880067d45900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff880067d45980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff880067d45a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff880067d45a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff880067d45b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Fixes: ead666000a ("media: dvb_frontend: only use kref after initialized")

Reported-by: Andrey Konovalov <andreyknvl@google.com>
Suggested-by: Matthias Schwarzott <zzam@gentoo.org>
Tested-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
2017-11-07 08:39:39 -05:00
arch media: arm: dts: omap3: N9/N950: Add flash references to the camera 2017-10-31 14:07:42 -04:00
block bio_copy_user_iov(): don't ignore ->iov_offset 2017-10-10 23:55:14 -04:00
certs modsign: add markers to endif-statements in certs/Makefile 2017-07-14 11:01:37 +10:00
crypto crypto: shash - Fix zero-length shash ahash digest crash 2017-10-11 00:34:07 +08:00
Documentation media: dt: bindings: smiapp: Document lens-focus and flash-leds properties 2017-10-31 14:04:45 -04:00
drivers dvb_frontend: don't use-after-free the frontend struct 2017-11-07 08:39:39 -05:00
firmware firmware: Restore support for built-in firmware 2017-09-16 10:58:48 -07:00
fs fs/binfmt_misc.c: node could be NULL when evicting inode 2017-10-13 16:18:33 -07:00
include media: v4l2-fwnode: use a typedef for a function callback 2017-11-01 12:25:28 -04:00
init Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-09-14 18:54:01 -07:00
ipc fix a typo in put_compat_shm_info() 2017-09-25 20:41:46 -04:00
kernel Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-10-14 15:20:38 -04:00
lib Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-10-14 15:14:20 -04:00
mm mm, swap: use page-cluster as max window of VMA based swap readahead 2017-10-13 16:18:33 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-10-09 16:25:00 -07:00
samples [media] media: v4l2-pci-skeleton: Fix error handling path in 'skeleton_probe()' 2017-10-04 16:55:02 -03:00
scripts scripts/kallsyms.c: ignore symbol type 'n' 2017-10-13 16:18:32 -07:00
security lsm: fix smack_inode_removexattr and xattr_getsecurity memleak 2017-10-04 18:03:15 +11:00
sound ALSA: caiaq: Fix stray URB at probe error path 2017-10-11 17:01:18 +02:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-10-14 15:16:49 -04:00
usr ramfs: clarify help text that compression applies to ramfs as well as legacy ramdisk. 2017-07-06 16:24:30 -07:00
virt Revert "KVM: Don't accept obviously wrong gsi values via KVM_IRQFD" 2017-09-19 08:37:17 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support to generate LLVM assembly files 2017-04-25 08:13:52 +09:00
.mailmap Update James Hogan's email address 2017-10-04 17:11:53 -07:00
COPYING
CREDITS selinux/stable-4.14 PR 20170831 2017-09-12 13:21:00 -07:00
Kbuild kbuild: Consolidate header generation from ASM offset information 2017-04-13 05:43:37 +09:00
Kconfig
MAINTAINERS media: tegra-cec: add Tegra HDMI CEC driver 2017-10-27 15:48:57 +02:00
Makefile Linux 4.14-rc5 2017-10-15 21:01:12 -04:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README 

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.