Hi Hillf, On Thu, Jan 23, 2020 at 06:27:07PM +0800, Hillf Danton wrote: > Wed, 22 Jan 2020 14:58:08 -0800 (PST) > > syzbot has found a reproducer for the following crash on: > > > > HEAD commit: 4cc301ee usb: gadget: add raw-gadget interface > > git tree: https://github.com/google/kasan.git usb-fuzzer > > console output: https://syzkaller.appspot.com/x/log.txt?x=17f5a721e00000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=9ba75825443d54bd > > dashboard link: https://syzkaller.appspot.com/bug?extid=75287f75e2fedd69d680 > > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16a0b6f1e00000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1327dd76e00000 > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > Reported-by: syzbot+75287f75e2fedd69d680@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > usbvision_set_audio: can't write iopin register for audio switching > > usbvision_radio_close: Final disconnect > > ================================================================== > > BUG: KASAN: use-after-free in v4l2_release+0x2f1/0x390 drivers/media/v4l2-core/v4l2-dev.c:459 > > Read of size 4 at addr ffff8881caba1068 by task v4l_id/1913 > > > > CPU: 1 PID: 1913 Comm: v4l_id Not tainted 5.5.0-rc6-syzkaller #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > > Call Trace: > > __dump_stack lib/dump_stack.c:77 [inline] > > dump_stack+0xef/0x16e lib/dump_stack.c:118 > > print_address_description.constprop.0.cold+0xd3/0x314 mm/kasan/report.c:374 > > __kasan_report.cold+0x37/0x85 mm/kasan/report.c:506 > > kasan_report+0xe/0x20 mm/kasan/common.c:639 > > v4l2_release+0x2f1/0x390 drivers/media/v4l2-core/v4l2-dev.c:459 > > __fput+0x2d7/0x840 fs/file_table.c:280 > > task_work_run+0x13f/0x1c0 kernel/task_work.c:113 > > tracehook_notify_resume include/linux/tracehook.h:188 [inline] > > exit_to_usermode_loop+0x1d2/0x200 arch/x86/entry/common.c:164 > > prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] > > syscall_return_slowpath arch/x86/entry/common.c:278 [inline] > > do_syscall_64+0x4e0/0x5a0 arch/x86/entry/common.c:304 > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > RIP: 0033:0x7fbeb0b822b0 > > Code: 40 75 0b 31 c0 48 83 c4 08 e9 0c ff ff ff 48 8d 3d c5 32 08 00 e8 c0 07 02 00 83 3d 45 a3 2b 00 00 75 10 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 ce 8a 01 00 48 89 04 24 > > RSP: 002b:00007ffe52d6b158 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 > > RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007fbeb0b822b0 > > RDX: 0000000000000013 RSI: 0000000080685600 RDI: 0000000000000003 > > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000400884 > > R13: 00007ffe52d6b2b0 R14: 0000000000000000 R15: 0000000000000000 > > > > Allocated by task 94: > > save_stack+0x1b/0x80 mm/kasan/common.c:72 > > set_track mm/kasan/common.c:80 [inline] > > __kasan_kmalloc mm/kasan/common.c:513 [inline] > > __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:486 > > kmalloc include/linux/slab.h:556 [inline] > > kzalloc include/linux/slab.h:670 [inline] > > usbvision_alloc drivers/media/usb/usbvision/usbvision-video.c:1315 [inline] > > usbvision_probe.cold+0x5c5/0x1f21 drivers/media/usb/usbvision/usbvision-video.c:1469 > > usb_probe_interface+0x310/0x800 drivers/usb/core/driver.c:361 > > really_probe+0x290/0xad0 drivers/base/dd.c:548 > > driver_probe_device+0x223/0x350 drivers/base/dd.c:721 > > __device_attach_driver+0x1d1/0x290 drivers/base/dd.c:828 > > bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430 > > __device_attach+0x217/0x390 drivers/base/dd.c:894 > > bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490 > > device_add+0x1459/0x1bf0 drivers/base/core.c:2487 > > usb_set_configuration+0xe47/0x17d0 drivers/usb/core/message.c:2023 > > generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210 > > usb_probe_device+0xaf/0x140 drivers/usb/core/driver.c:266 > > really_probe+0x290/0xad0 drivers/base/dd.c:548 > > driver_probe_device+0x223/0x350 drivers/base/dd.c:721 > > __device_attach_driver+0x1d1/0x290 drivers/base/dd.c:828 > > bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430 > > __device_attach+0x217/0x390 drivers/base/dd.c:894 > > bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490 > > device_add+0x1459/0x1bf0 drivers/base/core.c:2487 > > usb_new_device.cold+0x540/0xcd0 drivers/usb/core/hub.c:2537 > > hub_port_connect drivers/usb/core/hub.c:5184 [inline] > > hub_port_connect_change drivers/usb/core/hub.c:5324 [inline] > > port_event drivers/usb/core/hub.c:5470 [inline] > > hub_event+0x21cb/0x4300 drivers/usb/core/hub.c:5552 > > process_one_work+0x945/0x15c0 kernel/workqueue.c:2264 > > process_scheduled_works kernel/workqueue.c:2326 [inline] > > worker_thread+0x7ab/0xe20 kernel/workqueue.c:2412 > > kthread+0x318/0x420 kernel/kthread.c:255 > > ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 > > > > Freed by task 1913: > > save_stack+0x1b/0x80 mm/kasan/common.c:72 > > set_track mm/kasan/common.c:80 [inline] > > kasan_set_free_info mm/kasan/common.c:335 [inline] > > __kasan_slab_free+0x117/0x160 mm/kasan/common.c:474 > > slab_free_hook mm/slub.c:1425 [inline] > > slab_free_freelist_hook mm/slub.c:1458 [inline] > > slab_free mm/slub.c:3005 [inline] > > kfree+0xd5/0x300 mm/slub.c:3957 > > usbvision_release+0x181/0x1c0 drivers/media/usb/usbvision/usbvision-video.c:1364 > > usbvision_radio_close.cold+0x2b/0x74 drivers/media/usb/usbvision/usbvision-video.c:1130 > > v4l2_release+0x2e7/0x390 drivers/media/v4l2-core/v4l2-dev.c:455 > > __fput+0x2d7/0x840 fs/file_table.c:280 > > task_work_run+0x13f/0x1c0 kernel/task_work.c:113 > > tracehook_notify_resume include/linux/tracehook.h:188 [inline] > > exit_to_usermode_loop+0x1d2/0x200 arch/x86/entry/common.c:164 > > prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] > > syscall_return_slowpath arch/x86/entry/common.c:278 [inline] > > do_syscall_64+0x4e0/0x5a0 arch/x86/entry/common.c:304 > > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > > > The buggy address belongs to the object at ffff8881caba0000 > > which belongs to the cache kmalloc-8k of size 8192 > > The buggy address is located 4200 bytes inside of > > 8192-byte region [ffff8881caba0000, ffff8881caba2000) > > The buggy address belongs to the page: > > page:ffffea00072ae800 refcount:1 mapcount:0 mapping:ffff8881da00c500 index:0x0 compound_mapcount: 0 > > raw: 0200000000010200 dead000000000100 dead000000000122 ffff8881da00c500 > > raw: 0000000000000000 0000000080020002 00000001ffffffff 0000000000000000 > > page dumped because: kasan: bad access detected > > > > Memory state around the buggy address: > > ffff8881caba0f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ffff8881caba0f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > >ffff8881caba1000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ^ > > ffff8881caba1080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ffff8881caba1100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ================================================================== > > > Add the release callback for usbvision video device and use it to release > resources when the last reference to the device goes away. Would you be able to submit this with a commit message and your Signed-off-by line ? > --- a/drivers/media/usb/usbvision/usbvision-video.c > +++ b/drivers/media/usb/usbvision/usbvision-video.c > @@ -401,7 +401,6 @@ static int usbvision_v4l2_close(struct f > > if (r) { > printk(KERN_INFO "%s: Final disconnect\n", __func__); > - usbvision_release(usbvision); > return 0; > } > > @@ -409,6 +408,11 @@ static int usbvision_v4l2_close(struct f > return v4l2_fh_release(file); > } > > +static void usbvision_video_device_release(struct video_device *vdev) > +{ > + struct usb_usbvision *usbvision = video_get_drvdata(vdev); > + usbvision_release(usbvision); > +} > > /* > * usbvision_ioctl() > @@ -1181,7 +1185,7 @@ static struct video_device usbvision_vid > .fops = &usbvision_fops, > .ioctl_ops = &usbvision_ioctl_ops, > .name = "usbvision-video", > - .release = video_device_release_empty, > + .release = usbvision_video_device_release, > .tvnorms = USBVISION_NORMS, > }; > > --- a/drivers/media/v4l2-core/v4l2-dev.c > +++ b/drivers/media/v4l2-core/v4l2-dev.c > @@ -206,7 +206,10 @@ static void v4l2_device_release(struct d > } > #endif > > - /* Do not call v4l2_device_put if there is no release callback set. > + /* > + * Decrease v4l2_device refcount > + * > + * Do not call v4l2_device_put if there is no release callback set. > * Drivers that have no v4l2_device release callback might free the > * v4l2_dev instance in the video_device release callback below, so we > * must perform this check here. > @@ -214,16 +217,12 @@ static void v4l2_device_release(struct d > * TODO: In the long run all drivers that use v4l2_device should use the > * v4l2_device release callback. This check will then be unnecessary. > */ > - if (v4l2_dev->release == NULL) > - v4l2_dev = NULL; > + if (v4l2_dev->release) > + v4l2_device_put(v4l2_dev); > > /* Release video_device and perform other > cleanups as needed. */ > vdev->release(vdev); > - > - /* Decrease v4l2_device refcount */ > - if (v4l2_dev) > - v4l2_device_put(v4l2_dev); > } > > static struct class video_class = { -- Regards, Laurent Pinchart
