[syzbot] [nfs?] memory leak in percpu_ref_init

syzbot
2025-12-16T07:33:33Z

Hello,

syzbot found the following issue on:

HEAD commit: d358e5254674 Merge tag 'for-6.19/dm-changes' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=176f561a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9a0268003e02068d
dashboard link: https://syzkaller.appspot.com/bug?extid=6ee3b889bdeada0a6226
compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15a6661a580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11d4a1b4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e79f317bb571/disk-d358e525.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cf9e2849af10/vmlinux-d358e525.xz
kernel image: https://storage.googleapis.com/syzbot-assets/73d80a967038/bzImage-d358e525.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6ee3b889bdeada0a6226@syzkaller.appspotmail.com

BUG: memory leak
unreferenced object (percpu) 0x607e4d6bd360 (size 8):
comm "syz.0.17", pid 6093, jiffies 4294942369
hex dump (first 8 bytes on cpu 0):
00 00 00 00 00 00 00 00 ........
backtrace (crc 0):
pcpu_alloc_noprof+0x82c/0xd60 mm/percpu.c:1890
percpu_ref_init+0x36/0x1e0 lib/percpu-refcount.c:72
nfsd_create_serv+0xbe/0x260 fs/nfsd/nfssvc.c:605
nfsd_nl_listener_set_doit+0x62/0xb00 fs/nfsd/nfsctl.c:1882
genl_family_rcv_msg_doit+0x11e/0x190 net/netlink/genetlink.c:1115
genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
genl_rcv_msg+0x2fd/0x440 net/netlink/genetlink.c:1210
netlink_rcv_skb+0x93/0x1d0 net/netlink/af_netlink.c:2550
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x3a3/0x4f0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x335/0x6b0 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
____sys_sendmsg+0x562/0x5a0 net/socket.c:2592
___sys_sendmsg+0xc8/0x130 net/socket.c:2646
__sys_sendmsg+0xc7/0x140 net/socket.c:2678
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xa4/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object 0xffff88812a39dfc0 (size 64):
comm "syz.0.17", pid 6093, jiffies 4294942369
hex dump (first 32 bytes):
01 00 00 00 00 00 00 80 80 59 d7 81 ff ff ff ff .........Y......
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace (crc a2262fc6):
kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
slab_post_alloc_hook mm/slub.c:4958 [inline]
slab_alloc_node mm/slub.c:5263 [inline]
__kmalloc_cache_noprof+0x3b2/0x570 mm/slub.c:5771
kmalloc_noprof include/linux/slab.h:957 [inline]
kzalloc_noprof include/linux/slab.h:1094 [inline]
percpu_ref_init+0x94/0x1e0 lib/percpu-refcount.c:76
nfsd_create_serv+0xbe/0x260 fs/nfsd/nfssvc.c:605
nfsd_nl_listener_set_doit+0x62/0xb00 fs/nfsd/nfsctl.c:1882
genl_family_rcv_msg_doit+0x11e/0x190 net/netlink/genetlink.c:1115
genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
genl_rcv_msg+0x2fd/0x440 net/netlink/genetlink.c:1210
netlink_rcv_skb+0x93/0x1d0 net/netlink/af_netlink.c:2550
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x3a3/0x4f0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x335/0x6b0 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
____sys_sendmsg+0x562/0x5a0 net/socket.c:2592
___sys_sendmsg+0xc8/0x130 net/socket.c:2646
__sys_sendmsg+0xc7/0x140 net/socket.c:2678
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xa4/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object (percpu) 0x607e4d6bd368 (size 8):
comm "syz.0.18", pid 6095, jiffies 4294942370
hex dump (first 8 bytes on cpu 0):
00 00 00 00 00 00 00 00 ........
backtrace (crc 0):
pcpu_alloc_noprof+0x82c/0xd60 mm/percpu.c:1890
percpu_ref_init+0x36/0x1e0 lib/percpu-refcount.c:72
nfsd_create_serv+0xbe/0x260 fs/nfsd/nfssvc.c:605
nfsd_nl_listener_set_doit+0x62/0xb00 fs/nfsd/nfsctl.c:1882
genl_family_rcv_msg_doit+0x11e/0x190 net/netlink/genetlink.c:1115
genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
genl_rcv_msg+0x2fd/0x440 net/netlink/genetlink.c:1210
netlink_rcv_skb+0x93/0x1d0 net/netlink/af_netlink.c:2550
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x3a3/0x4f0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x335/0x6b0 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
____sys_sendmsg+0x562/0x5a0 net/socket.c:2592
___sys_sendmsg+0xc8/0x130 net/socket.c:2646
__sys_sendmsg+0xc7/0x140 net/socket.c:2678
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xa4/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object 0xffff88812833c840 (size 64):
comm "syz.0.18", pid 6095, jiffies 4294942370
hex dump (first 32 bytes):
01 00 00 00 00 00 00 80 80 59 d7 81 ff ff ff ff .........Y......
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace (crc a2262fc6):
kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
slab_post_alloc_hook mm/slub.c:4958 [inline]
slab_alloc_node mm/slub.c:5263 [inline]
__kmalloc_cache_noprof+0x3b2/0x570 mm/slub.c:5771
kmalloc_noprof include/linux/slab.h:957 [inline]
kzalloc_noprof include/linux/slab.h:1094 [inline]
percpu_ref_init+0x94/0x1e0 lib/percpu-refcount.c:76
nfsd_create_serv+0xbe/0x260 fs/nfsd/nfssvc.c:605
nfsd_nl_listener_set_doit+0x62/0xb00 fs/nfsd/nfsctl.c:1882
genl_family_rcv_msg_doit+0x11e/0x190 net/netlink/genetlink.c:1115
genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
genl_rcv_msg+0x2fd/0x440 net/netlink/genetlink.c:1210
netlink_rcv_skb+0x93/0x1d0 net/netlink/af_netlink.c:2550
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x3a3/0x4f0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x335/0x6b0 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
____sys_sendmsg+0x562/0x5a0 net/socket.c:2592
___sys_sendmsg+0xc8/0x130 net/socket.c:2646
__sys_sendmsg+0xc7/0x140 net/socket.c:2678
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xa4/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

connection error: failed to recv *flatrpc.ExecutorMessageRawT: read tcp 127.0.0.1:36571->127.0.0.1:45172: read: connection reset by peer

---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup