linux-kernel - [syzbot] [lsm?] memory leak in prepare

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Message-ID: <690d9fd4.a70a0220.22f260.0023.GAE@google.com>
Date: Thu, 06 Nov 2025 23:29:24 -0800
From: syzbot <syzbot+099461f8558eb0a1f4f3@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org, 
	paul@...l-moore.com, sergeh@...nel.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [lsm?] memory leak in prepare_creds (5)

Hello,

syzbot found the following issue on:

HEAD commit:    c2c2ccfd4ba7 Merge tag 'net-6.18-rc5' of git://git.kernel...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13d6ca92580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=cb128cd5cb439809
dashboard link: https://syzkaller.appspot.com/bug?extid=099461f8558eb0a1f4f3
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=11ac7012580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12aa10b4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b0451ba3fe41/disk-c2c2ccfd.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d3e8c67119ab/vmlinux-c2c2ccfd.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1d8e176e5054/bzImage-c2c2ccfd.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+099461f8558eb0a1f4f3@...kaller.appspotmail.com

2025/11/07 06:07:22 executed programs: 5
BUG: memory leak
unreferenced object 0xffff888101ad8900 (size 184):
  comm "syz-executor", pid 5986, jiffies 4294942797
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace (crc 45b79b1):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4975 [inline]
    slab_alloc_node mm/slub.c:5280 [inline]
    kmem_cache_alloc_noprof+0x397/0x5a0 mm/slub.c:5287
    prepare_creds+0x22/0x4f0 kernel/cred.c:212
    copy_creds+0x44/0x290 kernel/cred.c:312
    copy_process+0x706/0x27d0 kernel/fork.c:2046
    kernel_clone+0x119/0x6c0 kernel/fork.c:2609
    __do_sys_clone+0x7b/0xb0 kernel/fork.c:2750
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xa4/0xfa0 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object 0xffff88810096ace0 (size 32):
  comm "syz-executor", pid 5986, jiffies 4294942797
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    f8 f2 85 00 81 88 ff ff 00 00 00 00 00 00 00 00  ................
  backtrace (crc 894df7a1):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4975 [inline]
    slab_alloc_node mm/slub.c:5280 [inline]
    __do_kmalloc_node mm/slub.c:5641 [inline]
    __kmalloc_noprof+0x3e3/0x6b0 mm/slub.c:5654
    kmalloc_noprof include/linux/slab.h:961 [inline]
    kzalloc_noprof include/linux/slab.h:1094 [inline]
    lsm_blob_alloc+0x4d/0x70 security/security.c:690
    lsm_cred_alloc security/security.c:707 [inline]
    security_prepare_creds+0x30/0x270 security/security.c:3310
    prepare_creds+0x346/0x4f0 kernel/cred.c:242
    copy_creds+0x44/0x290 kernel/cred.c:312
    copy_process+0x706/0x27d0 kernel/fork.c:2046
    kernel_clone+0x119/0x6c0 kernel/fork.c:2609
    __do_sys_clone+0x7b/0xb0 kernel/fork.c:2750
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xa4/0xfa0 arch/x86/entry/syscall_64.c:94
    entry_SYSCALL_64_after_hwframe+0x77/0x7f

BUG: memory leak
unreferenced object 0xffff888128f3ca00 (size 1264):
  comm "kworker/1:1", pid 42, jiffies 4294942797
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    28 00 0b 40 00 00 00 00 00 00 00 00 00 00 00 00  (..@............
  backtrace (crc fdfa4398):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4975 [inline]
    slab_alloc_node mm/slub.c:5280 [inline]
    kmem_cache_alloc_noprof+0x397/0x5a0 mm/slub.c:5287
    sk_prot_alloc+0x3e/0x1b0 net/core/sock.c:2233
    sk_alloc+0x36/0x360 net/core/sock.c:2295
    __vsock_create.constprop.0+0x38/0x2f0 net/vmw_vsock/af_vsock.c:788
    virtio_transport_recv_listen net/vmw_vsock/virtio_transport_common.c:1527 [inline]
    virtio_transport_recv_pkt+0x7fd/0xf30 net/vmw_vsock/virtio_transport_common.c:1655
    vsock_loopback_work+0xfe/0x140 net/vmw_vsock/vsock_loopback.c:133
    process_one_work+0x26b/0x620 kernel/workqueue.c:3263
    process_scheduled_works kernel/workqueue.c:3346 [inline]
    worker_thread+0x2c4/0x4f0 kernel/workqueue.c:3427
    kthread+0x15b/0x310 kernel/kthread.c:463
    ret_from_fork+0x210/0x240 arch/x86/kernel/process.c:158
    ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

BUG: memory leak
unreferenced object 0xffff888146540100 (size 32):
  comm "kworker/1:1", pid 42, jiffies 4294942797
  hex dump (first 32 bytes):
    f8 f2 85 00 81 88 ff ff 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace (crc e7cc8a40):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4975 [inline]
    slab_alloc_node mm/slub.c:5280 [inline]
    __do_kmalloc_node mm/slub.c:5641 [inline]
    __kmalloc_noprof+0x3e3/0x6b0 mm/slub.c:5654
    kmalloc_noprof include/linux/slab.h:961 [inline]
    kzalloc_noprof include/linux/slab.h:1094 [inline]
    lsm_blob_alloc+0x4d/0x70 security/security.c:690
    lsm_sock_alloc security/security.c:4922 [inline]
    security_sk_alloc+0x30/0x270 security/security.c:4938
    sk_prot_alloc+0x8f/0x1b0 net/core/sock.c:2242
    sk_alloc+0x36/0x360 net/core/sock.c:2295
    __vsock_create.constprop.0+0x38/0x2f0 net/vmw_vsock/af_vsock.c:788
    virtio_transport_recv_listen net/vmw_vsock/virtio_transport_common.c:1527 [inline]
    virtio_transport_recv_pkt+0x7fd/0xf30 net/vmw_vsock/virtio_transport_common.c:1655
    vsock_loopback_work+0xfe/0x140 net/vmw_vsock/vsock_loopback.c:133
    process_one_work+0x26b/0x620 kernel/workqueue.c:3263
    process_scheduled_works kernel/workqueue.c:3346 [inline]
    worker_thread+0x2c4/0x4f0 kernel/workqueue.c:3427
    kthread+0x15b/0x310 kernel/kthread.c:463
    ret_from_fork+0x210/0x240 arch/x86/kernel/process.c:158
    ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

BUG: memory leak
unreferenced object 0xffff888109c274e0 (size 96):
  comm "kworker/1:1", pid 42, jiffies 4294942797
  hex dump (first 32 bytes):
    00 ca f3 28 81 88 ff ff 00 00 00 00 00 00 00 00  ...(............
    00 00 00 00 00 00 00 00 00 00 04 00 00 00 00 00  ................
  backtrace (crc 4f48ed20):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4975 [inline]
    slab_alloc_node mm/slub.c:5280 [inline]
    __kmalloc_cache_noprof+0x3a6/0x5b0 mm/slub.c:5758
    kmalloc_noprof include/linux/slab.h:957 [inline]
    kzalloc_noprof include/linux/slab.h:1094 [inline]
    virtio_transport_do_socket_init+0x2b/0xf0 net/vmw_vsock/virtio_transport_common.c:910
    vsock_assign_transport+0x31b/0x3a0 net/vmw_vsock/af_vsock.c:537
    virtio_transport_recv_listen net/vmw_vsock/virtio_transport_common.c:1545 [inline]
    virtio_transport_recv_pkt+0x861/0xf30 net/vmw_vsock/virtio_transport_common.c:1655
    vsock_loopback_work+0xfe/0x140 net/vmw_vsock/vsock_loopback.c:133
    process_one_work+0x26b/0x620 kernel/workqueue.c:3263
    process_scheduled_works kernel/workqueue.c:3346 [inline]
    worker_thread+0x2c4/0x4f0 kernel/workqueue.c:3427
    kthread+0x15b/0x310 kernel/kthread.c:463
    ret_from_fork+0x210/0x240 arch/x86/kernel/process.c:158
    ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

BUG: memory leak
unreferenced object 0xffff888101a80f00 (size 184):
  comm "syz-executor", pid 5986, jiffies 4294942798
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace (crc 51e903bf):
    kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
    slab_post_alloc_hook mm/slub.c:4975 [inline]
    slab_alloc_node mm/slub.c:5280 [inline]
    kmem_cache_alloc_noprof+0x397/0x5a0 mm/slub.c:5287
    prepare_creds+0x22/0x4f0 kernel/cred.c:212
    copy_creds+0x44/0x290 kernel/cred.c:312
    copy_process+0x706/0x27d0 kernel/fork.c:2046
    kernel_clone+0x119/0x6c0 kernel/fork.c:2609
    __do_sys_clone+0x7b/0xb0 kernel/fork.c:2750
    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
    do_syscall_64+0xa4/0xfa0 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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