[syzbot] [usb?] memory leak in try_get_usb_function_instance

[syzbot] [usb?] memory leak in try_get_usb_function_instance

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    3dab139d4795 Merge tag 'rust-fixes-7.2-2' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=163a388e580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ba7c2d1679fb08a2
dashboard link: https://syzkaller.appspot.com/bug?extid=eaa106d192c9daf37f95
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=111c11b9580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12b5909e580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8c49d395f8d0/disk-3dab139d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/deff2ace5e6a/vmlinux-3dab139d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2c90a783f940/bzImage-3dab139d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+eaa106d192c9daf37f95@syzkaller.appspotmail.com

2026/07/26 12:12:48 executed programs: 5
BUG: memory leak
unreferenced object 0xffff888112a69c00 (size 512):
  comm "syz.0.19", pid 5954, jiffies 4294946869
  hex dump (first 32 bytes):
    08 9c a6 12 81 88 ff ff 65 70 2e 30 00 00 00 00  ........ep.0....
    00 00 00 00 00 00 00 00 00 00 00 00 01 00 00 00  ................
  backtrace (crc 56e62c00):
    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]
    f_midi2_ep_opts_create drivers/usb/gadget/function/f_midi2.c:2504 [inline]
    f_midi2_alloc_inst+0xa0/0x250 drivers/usb/gadget/function/f_midi2.c:2666
    try_get_usb_function_instance+0xb8/0x100 drivers/usb/gadget/functions.c:28
    usb_get_function_instance+0x16/0x70 drivers/usb/gadget/functions.c:44
    function_make+0xf5/0x240 drivers/usb/gadget/configfs.c:626
    configfs_mkdir+0x2e9/0x6f0 fs/configfs/dir.c:1360
    vfs_mkdir+0x16c/0x3a0 fs/namei.c:5276
    filename_mkdirat+0x27c/0x300 fs/namei.c:5309
    __do_sys_mkdirat fs/namei.c:5330 [inline]
    __se_sys_mkdirat fs/namei.c:5327 [inline]
    __x64_sys_mkdirat+0x39/0x60 fs/namei.c:5327
    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 0xffff8881105a3f00 (size 256):
  comm "syz.0.19", pid 5954, jiffies 4294946869
  hex dump (first 32 bytes):
    08 3f 5a 10 81 88 ff ff 62 6c 6f 63 6b 2e 30 00  .?Z.....block.0.
    00 00 00 00 00 00 00 00 00 00 00 00 01 00 00 00  ................
  backtrace (crc f7f284e3):
    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]
    f_midi2_block_opts_create+0x82/0x120 drivers/usb/gadget/function/f_midi2.c:2342
    f_midi2_alloc_inst+0xe9/0x250 drivers/usb/gadget/function/f_midi2.c:2673
    try_get_usb_function_instance+0xb8/0x100 drivers/usb/gadget/functions.c:28
    usb_get_function_instance+0x16/0x70 drivers/usb/gadget/functions.c:44
    function_make+0xf5/0x240 drivers/usb/gadget/configfs.c:626
    configfs_mkdir+0x2e9/0x6f0 fs/configfs/dir.c:1360
    vfs_mkdir+0x16c/0x3a0 fs/namei.c:5276
    filename_mkdirat+0x27c/0x300 fs/namei.c:5309
    __do_sys_mkdirat fs/namei.c:5330 [inline]
    __se_sys_mkdirat fs/namei.c:5327 [inline]
    __x64_sys_mkdirat+0x39/0x60 fs/namei.c:5327
    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

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


---
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Re: [syzbot] [usb?] memory leak in try_get_usb_function_instance

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

drivers/usb/gadget/function/f_midi2.c:2643:57: error: 'struct usb_function_instance' has no member named 'groups'; did you mean 'group'?


Tested on:

commit:         11028ab6 Merge tag 'probes-fixes-v7.2-rc5' of git://gi..
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=ba7c2d1679fb08a2
dashboard link: https://syzkaller.appspot.com/bug?extid=eaa106d192c9daf37f95
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=17dc25b9580000

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

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+eaa106d192c9daf37f95@syzkaller.appspotmail.com
Tested-by: syzbot+eaa106d192c9daf37f95@syzkaller.appspotmail.com

Tested on:

commit:         11028ab6 Merge tag 'probes-fixes-v7.2-rc5' of git://gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16ad4aea580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ba7c2d1679fb08a2
dashboard link: https://syzkaller.appspot.com/bug?extid=eaa106d192c9daf37f95
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=137c25b9580000

Note: testing is done by a robot and is best-effort only.