Re: [syzbot] [usb?] memory leak in hidg_bind

[syzbot <syzbot+60740c6a17a5b5eb1f5a@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
memory leak in usb_get_function

2026/08/10 04:15:52 executed programs: 21
2026/08/10 04:15:58 executed programs: 23
2026/08/10 04:16:04 executed programs: 25
2026/08/10 04:16:09 executed programs: 27
BUG: memory leak
unreferenced object 0xffff888111f44000 (size 2048):
  comm "syz.0.37", pid 6720, jiffies 4294950131
  hex dump (first 32 bytes):
    00 00 01 01 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 04 00 01 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace (crc b745374a):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4597 [inline]
    slab_alloc_node mm/slub.c:4917 [inline]
    __kmalloc_cache_noprof+0x356/0x440 mm/slub.c:5485
    _kmalloc_noprof include/linux/slab.h:988 [inline]
    _kzalloc_noprof include/linux/slab.h:1309 [inline]
    hidg_alloc+0x2c/0x270 drivers/usb/gadget/function/f_hid.c:1603
    usb_get_function+0x21/0x60 drivers/usb/gadget/functions.c:61
    config_usb_cfg_link+0x10d/0x190 drivers/usb/gadget/configfs.c:469
    configfs_symlink+0x28c/0x860 fs/configfs/symlink.c:196
    vfs_symlink fs/namei.c:5660 [inline]
    vfs_symlink+0xd1/0x240 fs/namei.c:5639
    filename_symlinkat+0x17e/0x2b0 fs/namei.c:5685
    __do_sys_symlinkat fs/namei.c:5705 [inline]
    __se_sys_symlinkat fs/namei.c:5700 [inline]
    __x64_sys_symlinkat+0x47/0x70 fs/namei.c:5700
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xf8/0x610 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object 0xffff888114b800f8 (size 8):
  comm "syz.0.37", pid 6720, jiffies 4294950131
  hex dump (first 8 bytes):
    68 69 64 67 30 00 00 00                          hidg0...
  backtrace (crc 557cac88):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4597 [inline]
    slab_alloc_node mm/slub.c:4917 [inline]
    __do_kmalloc_node mm/slub.c:5333 [inline]
    __kmalloc_node_track_caller_noprof+0x3d3/0x570 mm/slub.c:5471
    kvasprintf+0x6e/0xf0 lib/kasprintf.c:25
    kvasprintf_const+0x5c/0x110 lib/kasprintf.c:49
    kobject_set_name_vargs+0x40/0xd0 lib/kobject.c:274
    dev_set_name+0x6d/0x90 drivers/base/core.c:3560
    hidg_alloc+0x132/0x270 drivers/usb/gadget/function/f_hid.c:1625
    usb_get_function+0x21/0x60 drivers/usb/gadget/functions.c:61
    config_usb_cfg_link+0x10d/0x190 drivers/usb/gadget/configfs.c:469
    configfs_symlink+0x28c/0x860 fs/configfs/symlink.c:196
    vfs_symlink fs/namei.c:5660 [inline]
    vfs_symlink+0xd1/0x240 fs/namei.c:5639
    filename_symlinkat+0x17e/0x2b0 fs/namei.c:5685
    __do_sys_symlinkat fs/namei.c:5705 [inline]
    __se_sys_symlinkat fs/namei.c:5700 [inline]
    __x64_sys_symlinkat+0x47/0x70 fs/namei.c:5700
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xf8/0x610 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object 0xffff888128bac500 (size 256):
  comm "syz.0.37", pid 6720, jiffies 4294950131
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 08 c5 ba 28 81 88 ff ff  ...........(....
    08 c5 ba 28 81 88 ff ff 00 ce 4e 83 ff ff ff ff  ...(......N.....
  backtrace (crc 57fd964b):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4597 [inline]
    slab_alloc_node mm/slub.c:4917 [inline]
    __kmalloc_cache_noprof+0x356/0x440 mm/slub.c:5485
    _kmalloc_noprof include/linux/slab.h:988 [inline]
    _kzalloc_noprof include/linux/slab.h:1309 [inline]
    device_private_init drivers/base/core.c:3602 [inline]
    device_add+0x740/0xc80 drivers/base/core.c:3653
    cdev_device_add+0x7e/0x100 fs/char_dev.c:553
    hidg_bind+0x385/0x490 drivers/usb/gadget/function/f_hid.c:1289
    usb_add_function+0xca/0x270 drivers/usb/gadget/composite.c:333
    configfs_composite_bind+0x667/0x9b0 drivers/usb/gadget/configfs.c:1796
    gadget_bind_driver+0xed/0x390 drivers/usb/gadget/udc/core.c:1662
    call_driver_probe drivers/base/dd.c:628 [inline]
    really_probe+0x12f/0x3a0 drivers/base/dd.c:706
    __driver_probe_device+0xe9/0x1a0 drivers/base/dd.c:868
    driver_probe_device+0x28/0xf0 drivers/base/dd.c:898
    __driver_attach drivers/base/dd.c:1292 [inline]
    __driver_attach+0x10a/0x200 drivers/base/dd.c:1232
    bus_for_each_dev+0xb8/0x120 drivers/base/bus.c:383
    bus_add_driver+0x122/0x280 drivers/base/bus.c:763
    driver_register+0xb1/0x140 drivers/base/driver.c:174
    usb_gadget_register_driver_owner+0x69/0xe0 drivers/usb/gadget/udc/core.c:1752
    gadget_dev_desc_UDC_store+0x153/0x1e0 drivers/usb/gadget/configfs.c:300

connection error: failed to recv *flatrpc.ExecutorMessageRawT: EOF


Tested on:

commit:         db2ddb87 Linux 7.2-rc7
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=123da079580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6843f8fd2336602d
dashboard link: https://syzkaller.appspot.com/bug?extid=60740c6a17a5b5eb1f5a
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
patch:          https://syzkaller.appspot.com/x/patch.diff?x=171462c6580000