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    Subject[PATCH 5.8 569/633] usb: gadget: function: printer: fix use-after-free in __lock_acquire
    Date
    From: Zqiang <qiang.zhang@windriver.com>

    [ Upstream commit e8d5f92b8d30bb4ade76494490c3c065e12411b1 ]

    Fix this by increase object reference count.

    BUG: KASAN: use-after-free in __lock_acquire+0x3fd4/0x4180
    kernel/locking/lockdep.c:3831
    Read of size 8 at addr ffff8880683b0018 by task syz-executor.0/3377

    CPU: 1 PID: 3377 Comm: syz-executor.0 Not tainted 5.6.11 #1
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
    Call Trace:
    __dump_stack lib/dump_stack.c:77 [inline]
    dump_stack+0xce/0x128 lib/dump_stack.c:118
    print_address_description.constprop.4+0x21/0x3c0 mm/kasan/report.c:374
    __kasan_report+0x131/0x1b0 mm/kasan/report.c:506
    kasan_report+0x12/0x20 mm/kasan/common.c:641
    __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135
    __lock_acquire+0x3fd4/0x4180 kernel/locking/lockdep.c:3831
    lock_acquire+0x127/0x350 kernel/locking/lockdep.c:4488
    __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
    _raw_spin_lock_irqsave+0x35/0x50 kernel/locking/spinlock.c:159
    printer_ioctl+0x4a/0x110 drivers/usb/gadget/function/f_printer.c:723
    vfs_ioctl fs/ioctl.c:47 [inline]
    ksys_ioctl+0xfb/0x130 fs/ioctl.c:763
    __do_sys_ioctl fs/ioctl.c:772 [inline]
    __se_sys_ioctl fs/ioctl.c:770 [inline]
    __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:770
    do_syscall_64+0x9e/0x510 arch/x86/entry/common.c:294
    entry_SYSCALL_64_after_hwframe+0x49/0xbe
    RIP: 0033:0x4531a9
    Code: ed 60 fc ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48
    89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d
    01 f0 ff ff 0f 83 bb 60 fc ff c3 66 2e 0f 1f 84 00 00 00 00
    RSP: 002b:00007fd14ad72c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
    RAX: ffffffffffffffda RBX: 000000000073bfa8 RCX: 00000000004531a9
    RDX: fffffffffffffff9 RSI: 000000000000009e RDI: 0000000000000003
    RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
    R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004bbd61
    R13: 00000000004d0a98 R14: 00007fd14ad736d4 R15: 00000000ffffffff

    Allocated by task 2393:
    save_stack+0x21/0x90 mm/kasan/common.c:72
    set_track mm/kasan/common.c:80 [inline]
    __kasan_kmalloc.constprop.3+0xa7/0xd0 mm/kasan/common.c:515
    kasan_kmalloc+0x9/0x10 mm/kasan/common.c:529
    kmem_cache_alloc_trace+0xfa/0x2d0 mm/slub.c:2813
    kmalloc include/linux/slab.h:555 [inline]
    kzalloc include/linux/slab.h:669 [inline]
    gprinter_alloc+0xa1/0x870 drivers/usb/gadget/function/f_printer.c:1416
    usb_get_function+0x58/0xc0 drivers/usb/gadget/functions.c:61
    config_usb_cfg_link+0x1ed/0x3e0 drivers/usb/gadget/configfs.c:444
    configfs_symlink+0x527/0x11d0 fs/configfs/symlink.c:202
    vfs_symlink+0x33d/0x5b0 fs/namei.c:4201
    do_symlinkat+0x11b/0x1d0 fs/namei.c:4228
    __do_sys_symlinkat fs/namei.c:4242 [inline]
    __se_sys_symlinkat fs/namei.c:4239 [inline]
    __x64_sys_symlinkat+0x73/0xb0 fs/namei.c:4239
    do_syscall_64+0x9e/0x510 arch/x86/entry/common.c:294
    entry_SYSCALL_64_after_hwframe+0x49/0xbe

    Freed by task 3368:
    save_stack+0x21/0x90 mm/kasan/common.c:72
    set_track mm/kasan/common.c:80 [inline]
    kasan_set_free_info mm/kasan/common.c:337 [inline]
    __kasan_slab_free+0x135/0x190 mm/kasan/common.c:476
    kasan_slab_free+0xe/0x10 mm/kasan/common.c:485
    slab_free_hook mm/slub.c:1444 [inline]
    slab_free_freelist_hook mm/slub.c:1477 [inline]
    slab_free mm/slub.c:3034 [inline]
    kfree+0xf7/0x410 mm/slub.c:3995
    gprinter_free+0x49/0xd0 drivers/usb/gadget/function/f_printer.c:1353
    usb_put_function+0x38/0x50 drivers/usb/gadget/functions.c:87
    config_usb_cfg_unlink+0x2db/0x3b0 drivers/usb/gadget/configfs.c:485
    configfs_unlink+0x3b9/0x7f0 fs/configfs/symlink.c:250
    vfs_unlink+0x287/0x570 fs/namei.c:4073
    do_unlinkat+0x4f9/0x620 fs/namei.c:4137
    __do_sys_unlink fs/namei.c:4184 [inline]
    __se_sys_unlink fs/namei.c:4182 [inline]
    __x64_sys_unlink+0x42/0x50 fs/namei.c:4182
    do_syscall_64+0x9e/0x510 arch/x86/entry/common.c:294
    entry_SYSCALL_64_after_hwframe+0x49/0xbe

    The buggy address belongs to the object at ffff8880683b0000
    which belongs to the cache kmalloc-1k of size 1024
    The buggy address is located 24 bytes inside of
    1024-byte region [ffff8880683b0000, ffff8880683b0400)
    The buggy address belongs to the page:
    page:ffffea0001a0ec00 refcount:1 mapcount:0 mapping:ffff88806c00e300
    index:0xffff8880683b1800 compound_mapcount: 0
    flags: 0x100000000010200(slab|head)
    raw: 0100000000010200 0000000000000000 0000000600000001 ffff88806c00e300
    raw: ffff8880683b1800 000000008010000a 00000001ffffffff 0000000000000000
    page dumped because: kasan: bad access detected

    Reported-by: Kyungtae Kim <kt0755@gmail.com>
    Signed-off-by: Zqiang <qiang.zhang@windriver.com>
    Signed-off-by: Felipe Balbi <balbi@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/usb/gadget/function/f_printer.c | 16 ++++++++++++++--
    1 file changed, 14 insertions(+), 2 deletions(-)

    diff --git a/drivers/usb/gadget/function/f_printer.c b/drivers/usb/gadget/function/f_printer.c
    index 9c7ed2539ff77..8ed1295d7e350 100644
    --- a/drivers/usb/gadget/function/f_printer.c
    +++ b/drivers/usb/gadget/function/f_printer.c
    @@ -31,6 +31,7 @@
    #include <linux/types.h>
    #include <linux/ctype.h>
    #include <linux/cdev.h>
    +#include <linux/kref.h>

    #include <asm/byteorder.h>
    #include <linux/io.h>
    @@ -64,7 +65,7 @@ struct printer_dev {
    struct usb_gadget *gadget;
    s8 interface;
    struct usb_ep *in_ep, *out_ep;
    -
    + struct kref kref;
    struct list_head rx_reqs; /* List of free RX structs */
    struct list_head rx_reqs_active; /* List of Active RX xfers */
    struct list_head rx_buffers; /* List of completed xfers */
    @@ -218,6 +219,13 @@ static inline struct usb_endpoint_descriptor *ep_desc(struct usb_gadget *gadget,

    /*-------------------------------------------------------------------------*/

    +static void printer_dev_free(struct kref *kref)
    +{
    + struct printer_dev *dev = container_of(kref, struct printer_dev, kref);
    +
    + kfree(dev);
    +}
    +
    static struct usb_request *
    printer_req_alloc(struct usb_ep *ep, unsigned len, gfp_t gfp_flags)
    {
    @@ -348,6 +356,7 @@ printer_open(struct inode *inode, struct file *fd)

    spin_unlock_irqrestore(&dev->lock, flags);

    + kref_get(&dev->kref);
    DBG(dev, "printer_open returned %x\n", ret);
    return ret;
    }
    @@ -365,6 +374,7 @@ printer_close(struct inode *inode, struct file *fd)
    dev->printer_status &= ~PRINTER_SELECTED;
    spin_unlock_irqrestore(&dev->lock, flags);

    + kref_put(&dev->kref, printer_dev_free);
    DBG(dev, "printer_close\n");

    return 0;
    @@ -1350,7 +1360,8 @@ static void gprinter_free(struct usb_function *f)
    struct f_printer_opts *opts;

    opts = container_of(f->fi, struct f_printer_opts, func_inst);
    - kfree(dev);
    +
    + kref_put(&dev->kref, printer_dev_free);
    mutex_lock(&opts->lock);
    --opts->refcnt;
    mutex_unlock(&opts->lock);
    @@ -1419,6 +1430,7 @@ static struct usb_function *gprinter_alloc(struct usb_function_instance *fi)
    return ERR_PTR(-ENOMEM);
    }

    + kref_init(&dev->kref);
    ++opts->refcnt;
    dev->minor = opts->minor;
    dev->pnp_string = opts->pnp_string;
    --
    2.25.1


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