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    Subject[PATCH 5.2 039/144] usb: yurex: Fix use-after-free in yurex_delete
    Date
    From: Suzuki K Poulose <suzuki.poulose@arm.com>

    commit fc05481b2fcabaaeccf63e32ac1baab54e5b6963 upstream.

    syzbot reported the following crash [0]:

    BUG: KASAN: use-after-free in usb_free_coherent+0x79/0x80
    drivers/usb/core/usb.c:928
    Read of size 8 at addr ffff8881b18599c8 by task syz-executor.4/16007

    CPU: 0 PID: 16007 Comm: syz-executor.4 Not tainted 5.3.0-rc2+ #23
    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+0xca/0x13e lib/dump_stack.c:113
    print_address_description+0x6a/0x32c mm/kasan/report.c:351
    __kasan_report.cold+0x1a/0x33 mm/kasan/report.c:482
    kasan_report+0xe/0x12 mm/kasan/common.c:612
    usb_free_coherent+0x79/0x80 drivers/usb/core/usb.c:928
    yurex_delete+0x138/0x330 drivers/usb/misc/yurex.c:100
    kref_put include/linux/kref.h:65 [inline]
    yurex_release+0x66/0x90 drivers/usb/misc/yurex.c:392
    __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:163
    prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
    syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
    do_syscall_64+0x45f/0x580 arch/x86/entry/common.c:299
    entry_SYSCALL_64_after_hwframe+0x49/0xbe
    RIP: 0033:0x413511
    Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48
    83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48
    89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
    RSP: 002b:00007ffc424ea2e0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
    RAX: 0000000000000000 RBX: 0000000000000007 RCX: 0000000000413511
    RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006
    RBP: 0000000000000001 R08: 0000000029a2fc22 R09: 0000000029a2fc26
    R10: 00007ffc424ea3c0 R11: 0000000000000293 R12: 000000000075c9a0
    R13: 000000000075c9a0 R14: 0000000000761938 R15: ffffffffffffffff

    Allocated by task 2776:
    save_stack+0x1b/0x80 mm/kasan/common.c:69
    set_track mm/kasan/common.c:77 [inline]
    __kasan_kmalloc mm/kasan/common.c:487 [inline]
    __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:460
    kmalloc include/linux/slab.h:552 [inline]
    kzalloc include/linux/slab.h:748 [inline]
    usb_alloc_dev+0x51/0xf95 drivers/usb/core/usb.c:583
    hub_port_connect drivers/usb/core/hub.c:5004 [inline]
    hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
    port_event drivers/usb/core/hub.c:5359 [inline]
    hub_event+0x15c0/0x3640 drivers/usb/core/hub.c:5441
    process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
    worker_thread+0x96/0xe20 kernel/workqueue.c:2415
    kthread+0x318/0x420 kernel/kthread.c:255
    ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

    Freed by task 16007:
    save_stack+0x1b/0x80 mm/kasan/common.c:69
    set_track mm/kasan/common.c:77 [inline]
    __kasan_slab_free+0x130/0x180 mm/kasan/common.c:449
    slab_free_hook mm/slub.c:1423 [inline]
    slab_free_freelist_hook mm/slub.c:1470 [inline]
    slab_free mm/slub.c:3012 [inline]
    kfree+0xe4/0x2f0 mm/slub.c:3953
    device_release+0x71/0x200 drivers/base/core.c:1064
    kobject_cleanup lib/kobject.c:693 [inline]
    kobject_release lib/kobject.c:722 [inline]
    kref_put include/linux/kref.h:65 [inline]
    kobject_put+0x171/0x280 lib/kobject.c:739
    put_device+0x1b/0x30 drivers/base/core.c:2213
    usb_put_dev+0x1f/0x30 drivers/usb/core/usb.c:725
    yurex_delete+0x40/0x330 drivers/usb/misc/yurex.c:95
    kref_put include/linux/kref.h:65 [inline]
    yurex_release+0x66/0x90 drivers/usb/misc/yurex.c:392
    __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:163
    prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
    syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
    do_syscall_64+0x45f/0x580 arch/x86/entry/common.c:299
    entry_SYSCALL_64_after_hwframe+0x49/0xbe

    The buggy address belongs to the object at ffff8881b1859980
    which belongs to the cache kmalloc-2k of size 2048
    The buggy address is located 72 bytes inside of
    2048-byte region [ffff8881b1859980, ffff8881b185a180)
    The buggy address belongs to the page:
    page:ffffea0006c61600 refcount:1 mapcount:0 mapping:ffff8881da00c000
    index:0x0 compound_mapcount: 0
    flags: 0x200000000010200(slab|head)
    raw: 0200000000010200 0000000000000000 0000000100000001 ffff8881da00c000
    raw: 0000000000000000 00000000000f000f 00000001ffffffff 0000000000000000
    page dumped because: kasan: bad access detected

    Memory state around the buggy address:
    ffff8881b1859880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
    ffff8881b1859900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
    > ffff8881b1859980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
    ^
    ffff8881b1859a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
    ffff8881b1859a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
    ==================================================================

    A quick look at the yurex_delete() shows that we drop the reference
    to the usb_device before releasing any buffers associated with the
    device. Delay the reference drop until we have finished the cleanup.

    [0] https://lore.kernel.org/lkml/0000000000003f86d8058f0bd671@google.com/

    Fixes: 6bc235a2e24a5e ("USB: add driver for Meywa-Denki & Kayac YUREX")
    Cc: Jiri Kosina <jkosina@suse.cz>
    Cc: Tomoki Sekiyama <tomoki.sekiyama@gmail.com>
    Cc: Oliver Neukum <oneukum@suse.com>
    Cc: andreyknvl@google.com
    Cc: gregkh@linuxfoundation.org
    Cc: Alan Stern <stern@rowland.harvard.edu>
    Cc: syzkaller-bugs@googlegroups.com
    Cc: dtor@chromium.org
    Reported-by: syzbot+d1fedb1c1fdb07fca507@syzkaller.appspotmail.com
    Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
    Cc: stable <stable@vger.kernel.org>
    Link: https://lore.kernel.org/r/20190805111528.6758-1-suzuki.poulose@arm.com
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/usb/misc/yurex.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/drivers/usb/misc/yurex.c
    +++ b/drivers/usb/misc/yurex.c
    @@ -92,7 +92,6 @@ static void yurex_delete(struct kref *kr

    dev_dbg(&dev->interface->dev, "%s\n", __func__);

    - usb_put_dev(dev->udev);
    if (dev->cntl_urb) {
    usb_kill_urb(dev->cntl_urb);
    kfree(dev->cntl_req);
    @@ -108,6 +107,7 @@ static void yurex_delete(struct kref *kr
    dev->int_buffer, dev->urb->transfer_dma);
    usb_free_urb(dev->urb);
    }
    + usb_put_dev(dev->udev);
    kfree(dev);
    }


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