Re: [syzbot] [fs?] [usb?] KASAN: slab-use-after-free Read in lockref_get (2)

[syzbot <syzbot+227dbc9afd022922d624@syzkaller.appspotmail.com>]

Hello,

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

m: mask: 0xffffff max_cycles: 0xffffff, max_idle_ns: 2085701024 ns
[    3.244305][    T1] NET: Registered PF_INET protocol family
[    3.247499][    T1] IP idents hash table entries: 131072 (order: 8, 1048576 bytes, vmalloc)
[    3.259218][    T1] tcp_listen_portaddr_hash hash table entries: 4096 (order: 7, 294912 bytes, vmalloc)
[    3.261261][    T1] Table-perturb hash table entries: 65536 (order: 6, 262144 bytes, vmalloc)
[    3.263274][    T1] TCP established hash table entries: 65536 (order: 7, 524288 bytes, vmalloc)
[    3.274524][    T1] TCP bind hash table entries: 65536 (order: 12, 9437184 bytes, vmalloc hugepage)
[    3.281391][    T1] TCP: Hash tables configured (established 65536 bind 65536)
[    3.284940][    T1] MPTCP token hash table entries: 8192 (order: 8, 720896 bytes, vmalloc)
[    3.288577][    T1] UDP hash table entries: 4096 (order: 8, 1048576 bytes, vmalloc)
[    3.291550][    T1] NET: Registered PF_UNIX/PF_LOCAL protocol family
[    3.306684][    T1] RPC: Registered named UNIX socket transport module.
[    3.307718][    T1] RPC: Registered udp transport module.
[    3.308513][    T1] RPC: Registered tcp transport module.
[    3.309357][    T1] RPC: Registered tcp-with-tls transport module.
[    3.310392][    T1] RPC: Registered tcp NFSv4.1 backchannel transport module.
[    3.316342][    T1] NET: Registered PF_XDP protocol family
[    3.317480][    T1] pci_bus 0000:00: resource 4 [io  0x0000-0x0cf7 window]
[    3.318551][    T1] pci_bus 0000:00: resource 5 [io  0x0d00-0x0fff window]
[    3.319885][    T1] pci_bus 0000:00: resource 6 [io  0xc000-0xffff window]
[    3.321388][    T1] pci_bus 0000:00: resource 7 [io  0xa000-0xbfff window]
[    3.322459][    T1] pci_bus 0000:00: resource 8 [mem 0x000a0000-0x000bffff window]
[    3.323839][    T1] pci_bus 0000:00: resource 9 [mem 0xc0000000-0xfebfefff window]
[    3.326592][    T1] pci 0000:00:00.0: Limiting direct PCI/PCI transfers
[    3.328327][    T1] PCI: CLS 0 bytes, default 64
[    3.329389][    T1] PCI-DMA: Using software bounce buffering for IO (SWIOTLB)
[    3.330474][    T1] software IO TLB: mapped [mem 0x00000000b4400000-0x00000000b8400000] (64MB)
[    3.333143][    T1] ACPI: bus type thunderbolt registered
[    3.341226][    T1] RAPL PMU: API unit is 2^-32 Joules, 0 fixed counters, 10737418240 ms ovfl timer
[    3.346936][   T59] kworker/u8:1 (59) used greatest stack depth: 27864 bytes left
[    3.364118][    T1] kvm_amd: CPU 1 isn't AMD or Hygon
[    3.365204][    T1] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x285d48fab19, max_idle_ns: 440795208084 ns
[    3.367725][    T1] clocksource: Switched to clocksource tsc
[    3.403452][    T1] Initialise system trusted keyrings
[    3.404162][   T84] kworker/u8:4 (84) used greatest stack depth: 27160 bytes left
[    3.407742][    T1] workingset: timestamp_bits=40 (anon: 35) max_order=21 bucket_order=0 (anon: 0)
[    3.415933][    T1] DLM installed
[    3.421490][    T1] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[    3.429626][    T1] NFS: Registering the id_resolver key type
[    3.430824][    T1] Key type id_resolver registered
[    3.431584][    T1] Key type id_legacy registered
[    3.432928][    T1] nfs4filelayout_init: NFSv4 File Layout Driver Registering...
[    3.434314][    T1] nfs4flexfilelayout_init: NFSv4 Flexfile Layout Driver Registering...
[    3.441599][    T1] smbdirect: subsystem loading...
[    3.448154][    T1] smbdirect: subsystem loaded
[    3.471719][    T1] Key type cifs.spnego registered
[    3.472760][    T1] Key type cifs.idmap registered
[    3.476921][    T1] ntfs3: Enabled Linux POSIX ACLs support
[    3.477738][    T1] ntfs3: Read-only LZX/Xpress compression included
[    3.478987][    T1] jffs2: version 2.2. (NAND) (SUMMARY)  © 2001-2006 Red Hat, Inc.
[    3.482637][    T1] romfs: ROMFS MTD (C) 2007 Red Hat, Inc.
[    3.483593][    T1] QNX4 filesystem 0.2.3 registered.
[    3.484738][    T1] qnx6: QNX6 filesystem 1.0.0 registered.
[    3.486442][    T1] fuse: init (API version 7.45)
[    3.489877][    T1] orangefs_debugfs_init: called with debug mask: :none: :0:
[    3.492401][    T1] orangefs_init: module version upstream loaded
[    3.494199][    T1] JFS: nTxBlock = 8192, nTxLock = 65536
[    3.507409][    T1] SGI XFS with ACLs, security attributes, realtime, scrub, repair, quota, no debug enabled
[    3.514958][    T1] 9p: Installing v9fs 9p2000 file system support
[    3.516652][    T1] NILFS version 2 loaded
[    3.517609][    T1] befs: version: 0.9.3
[    3.519354][    T1] ocfs2: Registered cluster interface o2cb
[    3.521201][    T1] ocfs2: Registered cluster interface user
[    3.523024][    T1] OCFS2 User DLM kernel interface loaded
[    3.545147][    T1] gfs2: GFS2 installed
[    3.560183][    T1] ceph: loaded (mds proto 32)
[    3.573563][    T1] NET: Registered PF_ALG protocol family
[    3.574709][    T1] async_tx: api initialized (async)
[    3.575970][    T1] Key type asymmetric registered
[    3.576921][    T1] Asymmetric key parser 'x509' registered
[    3.577745][    T1] Asymmetric key parser 'pkcs8' registered
[    3.578604][    T1] Key type pkcs7_test registered
[    3.579842][    T1] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 239)
[    3.583698][    T1] io scheduler mq-deadline registered
[    3.584626][    T1] io scheduler kyber registered
[    3.586119][    T1] io scheduler bfq registered
[    3.601298][    T1] input: Power Button as /devices/platform/LNXPWRBN:00/input/input0
[    3.605629][    T1] ACPI: button: Power Button [PWRF]
[    3.609215][    T1] input: Sleep Button as /devices/platform/LNXSLPBN:00/input/input1
[    3.611991][    T1] ACPI: button: Sleep Button [SLPF]
[    3.635978][    T1] ioatdma: Intel(R) QuickData Technology Driver 5.00
[    3.662181][   T10] ACPI: \_SB_.LNKC: Enabled at IRQ 11
[    3.663176][   T10] virtio-pci 0000:00:03.0: virtio_pci: leaving for legacy driver
[    3.694911][   T10] ACPI: \_SB_.LNKD: Enabled at IRQ 10
[    3.696705][   T10] virtio-pci 0000:00:04.0: virtio_pci: leaving for legacy driver
[    3.724400][   T10] ACPI: \_SB_.LNKB: Enabled at IRQ 10
[    3.725672][   T10] virtio-pci 0000:00:06.0: virtio_pci: leaving for legacy driver
[    4.062323][  T524] kworker/u8:7 (524) used greatest stack depth: 26904 bytes left
[    4.258630][    T1] N_HDLC line discipline registered with maxframe=4096
[    4.261364][    T1] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
[    4.275999][    T1] 00:02: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A
[    4.291450][    T1] 00:03: ttyS1 at I/O 0x2f8 (irq = 3, base_baud = 115200) is a 16550A
[    4.306966][    T1] 00:04: ttyS2 at I/O 0x3e8 (irq = 6, base_baud = 115200) is a 16550A
[    4.321856][    T1] 00:05: ttyS3 at I/O 0x2e8 (irq = 7, base_baud = 115200) is a 16550A
[    4.357497][    T1] Non-volatile memory driver v1.3
[    4.382848][    T1] usbcore: registered new interface driver xillyusb
[    4.391825][    T1] ACPI: bus type drm_connector registered
[    4.402882][    T1] [drm] Initialized vgem 1.0.0 for vgem on minor 0
[    4.408272][    T1] ------------[ cut here ]------------
[    4.409057][    T1] [PLANE:35:plane-0] pixel format with alpha exposed but blend mode not setup
[    4.409076][    T1] WARNING: drivers/gpu/drm/drm_mode_config.c:872 at drm_mode_config_validate+0xfb4/0x1be0, CPU#0: swapper/0/1
[    4.412353][    T1] Modules linked in:
[    4.412951][    T1] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full) 
[    4.414327][    T1] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/05/2026
[    4.415957][    T1] RIP: 0010:drm_mode_config_validate+0xfbb/0x1be0
[    4.416871][    T1] Code: 00 49 8b 57 18 48 89 f8 48 c1 e8 03 0f b6 04 28 84 c0 74 08 3c 03 0f 8e 00 0b 00 00 48 8d 3d fc 1e 81 0b 41 8b b7 c8 00 00 00 <67> 48 0f b9 3a e9 fa fd ff ff 48 8b 5c 24 20 e8 41 9b 3c fc 48 8d
[    4.420277][    T1] RSP: 0000:ffffc90000067c18 EFLAGS: 00010246
[    4.421416][    T1] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[    4.422525][    T1] RDX: ffff8880270d17e0 RSI: 0000000000000023 RDI: ffffffff914f9750
[    4.423790][    T1] RBP: dffffc0000000000 R08: 0000000000000001 R09: 0000000000000000
[    4.424912][    T1] R10: 0000000000000001 R11: 0000000000000000 R12: ffffed1004db7023
[    4.426628][    T1] R13: ffffed1004db7024 R14: 0000000000000001 R15: ffff888026db8028
[    4.427965][    T1] FS:  0000000000000000(0000) GS:ffff888123b83000(0000) knlGS:0000000000000000
[    4.429922][    T1] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    4.431232][    T1] CR2: ffff88823ffff000 CR3: 000000000eb94000 CR4: 00000000003526f0
[    4.432829][    T1] Call Trace:
[    4.433578][    T1]  <TASK>
[    4.434377][    T1]  drm_dev_register+0x56e/0x7b0
[    4.435116][    T1]  vkms_create+0x491/0x5b0
[    4.436303][    T1]  ? __pfx_vkms_init+0x10/0x10
[    4.437097][    T1]  vkms_init+0x98/0xe0
[    4.437725][    T1]  do_one_initcall+0x11c/0x6f0
[    4.438689][    T1]  ? __pfx_do_one_initcall+0x10/0x10
[    4.439912][    T1]  ? kasan_unpoison+0x15/0x60
[    4.440799][    T1]  ? kernel_init_freeable+0x4ca/0x7b0
[    4.441810][    T1]  kernel_init_freeable+0x6ea/0x7b0
[    4.442739][    T1]  ? __pfx_kernel_init+0x10/0x10
[    4.443755][    T1]  kernel_init+0x21/0x1e0
[    4.444481][    T1]  ? __pfx_kernel_init+0x10/0x10
[    4.445296][    T1]  ret_from_fork+0x730/0xd60
[    4.446009][    T1]  ? __pfx_ret_from_fork+0x10/0x10
[    4.446941][    T1]  ? __switch_to+0x800/0x10f0
[    4.448149][    T1]  ? __pfx_kernel_init+0x10/0x10
[    4.448847][    T1]  ret_from_fork_asm+0x1a/0x30
[    4.449585][    T1]  </TASK>
[    4.450241][    T1] Kernel panic - not syncing: kernel: panic_on_warn set ...
[    4.451670][    T1] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full) 
[    4.453007][    T1] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/05/2026
[    4.454566][    T1] Call Trace:
[    4.455144][    T1]  <TASK>
[    4.455713][    T1]  dump_stack_lvl+0x100/0x190
[    4.455982][    T1]  vpanic+0x553/0x970
[    4.455982][    T1]  ? __pfx_vpanic+0x10/0x10
[    4.455982][    T1]  panic+0xd1/0xe0
[    4.455982][    T1]  ? __pfx_panic+0x10/0x10
[    4.455982][    T1]  check_panic_on_warn.cold+0x19/0x34
[    4.455982][    T1]  ? drm_mode_config_validate+0xfb4/0x1be0
[    4.455982][    T1]  __warn.cold+0x191/0x318
[    4.455982][    T1]  __report_bug+0x30f/0x440
[    4.455982][    T1]  ? drm_mode_config_validate+0xfb4/0x1be0
[    4.455982][    T1]  ? __pfx___report_bug+0x10/0x10
[    4.455982][    T1]  ? __lock_acquire+0x4c5/0x1ec0
[    4.455982][    T1]  report_bug_entry+0xe2/0x290
[    4.455982][    T1]  ? drm_mode_config_validate+0xfbb/0x1be0
[    4.455982][    T1]  handle_bug+0x1cd/0x2a0
[    4.455982][    T1]  exc_invalid_op+0x17/0x50
[    4.455982][    T1]  asm_exc_invalid_op+0x1a/0x20
[    4.455982][    T1] RIP: 0010:drm_mode_config_validate+0xfbb/0x1be0
[    4.455982][    T1] Code: 00 49 8b 57 18 48 89 f8 48 c1 e8 03 0f b6 04 28 84 c0 74 08 3c 03 0f 8e 00 0b 00 00 48 8d 3d fc 1e 81 0b 41 8b b7 c8 00 00 00 <67> 48 0f b9 3a e9 fa fd ff ff 48 8b 5c 24 20 e8 41 9b 3c fc 48 8d
[    4.455982][    T1] RSP: 0000:ffffc90000067c18 EFLAGS: 00010246
[    4.455982][    T1] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[    4.455982][    T1] RDX: ffff8880270d17e0 RSI: 0000000000000023 RDI: ffffffff914f9750
[    4.455982][    T1] RBP: dffffc0000000000 R08: 0000000000000001 R09: 0000000000000000
[    4.455982][    T1] R10: 0000000000000001 R11: 0000000000000000 R12: ffffed1004db7023
[    4.455982][    T1] R13: ffffed1004db7024 R14: 0000000000000001 R15: ffff888026db8028
[    4.455982][    T1]  ? drm_mode_config_validate+0xf76/0x1be0
[    4.455982][    T1]  drm_dev_register+0x56e/0x7b0
[    4.455982][    T1]  vkms_create+0x491/0x5b0
[    4.455982][    T1]  ? __pfx_vkms_init+0x10/0x10
[    4.455982][    T1]  vkms_init+0x98/0xe0
[    4.455982][    T1]  do_one_initcall+0x11c/0x6f0
[    4.455982][    T1]  ? __pfx_do_one_initcall+0x10/0x10
[    4.455982][    T1]  ? kasan_unpoison+0x15/0x60
[    4.455982][    T1]  ? kernel_init_freeable+0x4ca/0x7b0
[    4.455982][    T1]  kernel_init_freeable+0x6ea/0x7b0
[    4.455982][    T1]  ? __pfx_kernel_init+0x10/0x10
[    4.455982][    T1]  kernel_init+0x21/0x1e0
[    4.455982][    T1]  ? __pfx_kernel_init+0x10/0x10
[    4.455982][    T1]  ret_from_fork+0x730/0xd60
[    4.455982][    T1]  ? __pfx_ret_from_fork+0x10/0x10
[    4.455982][    T1]  ? __switch_to+0x800/0x10f0
[    4.455982][    T1]  ? __pfx_kernel_init+0x10/0x10
[    4.455982][    T1]  ret_from_fork_asm+0x1a/0x30
[    4.455982][    T1]  </TASK>
[    4.455982][    T1] Kernel Offset: disabled
[    4.455982][    T1] Rebooting in 86400 seconds..


syzkaller build log:
go env (err=<nil>)
AR='ar'
CC='gcc'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='g++'
GCCGO='gccgo'
GO111MODULE='auto'
GOAMD64='v1'
GOARCH='amd64'
GOAUTH='netrc'
GOBIN=''
GOCACHE='/syzkaller/.cache/go-build'
GOCACHEPROG=''
GODEBUG=''
GOENV='/syzkaller/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFIPS140='off'
GOFLAGS=''
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build1331161525=/tmp/go-build -gno-record-gcc-switches'
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMOD='/syzkaller/jobs-2/linux/gopath/src/github.com/google/syzkaller/go.mod'
GOMODCACHE='/syzkaller/jobs-2/linux/gopath/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/syzkaller/jobs-2/linux/gopath'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTELEMETRY='local'
GOTELEMETRYDIR='/syzkaller/.config/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.26.0'
GOWORK=''
PKG_CONFIG='pkg-config'

git status (err=<nil>)
HEAD detached at 05b26a281c0
nothing to commit, working tree clean


tput: No value for $TERM and no -T specified
tput: No value for $TERM and no -T specified
Makefile:31: run command via tools/syz-env for best compatibility, see:
Makefile:32: https://github.com/google/syzkaller/blob/master/docs/contributing.md#using-syz-env
go list -f '{{.Stale}}' -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=05b26a281c072cc34dcad83a283fd2aeeff18ad1 -X github.com/google/syzkaller/prog.gitRevisionDate=20260724-140511"  ./sys/syz-sysgen | grep -q false || go install -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=05b26a281c072cc34dcad83a283fd2aeeff18ad1 -X github.com/google/syzkaller/prog.gitRevisionDate=20260724-140511"  ./sys/syz-sysgen
make .descriptions
tput: No value for $TERM and no -T specified
tput: No value for $TERM and no -T specified
Makefile:31: run command via tools/syz-env for best compatibility, see:
Makefile:32: https://github.com/google/syzkaller/blob/master/docs/contributing.md#using-syz-env
bin/syz-sysgen
touch .descriptions
GOOS=linux GOARCH=amd64 go build -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=05b26a281c072cc34dcad83a283fd2aeeff18ad1 -X github.com/google/syzkaller/prog.gitRevisionDate=20260724-140511"  -o ./bin/linux_amd64/syz-execprog github.com/google/syzkaller/tools/syz-execprog
mkdir -p ./bin/linux_amd64
g++ -o ./bin/linux_amd64/syz-executor executor/executor.cc \
	-m64 -O2 -pthread -Wall -Werror -Wparentheses -Wunused-const-variable -Wframe-larger-than=16384 -Wno-stringop-overflow -Wno-array-bounds -Wno-format-overflow -Wno-unused-but-set-variable -Wno-unused-command-line-argument -static-pie -std=c++17 -I. -Iexecutor/_include   -DGOOS_linux=1 -DGOARCH_amd64=1 \
	-DHOSTGOOS_linux=1 -DGIT_REVISION=\"05b26a281c072cc34dcad83a283fd2aeeff18ad1\"
/usr/bin/ld: /tmp/ccXjEkJ3.o: in function `Connection::Connect(char const*, char const*)':
executor.cc:(.text._ZN10Connection7ConnectEPKcS1_[_ZN10Connection7ConnectEPKcS1_]+0x386): warning: Using 'gethostbyname' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
./tools/check-syzos.sh 2>/dev/null


Error text is too large and was truncated, full error text is at:
https://syzkaller.appspot.com/x/error.txt?x=11d04625580000


Tested on:

commit:         66fb95a5 Merge tag 'caps-pr-20260820' of git://git.ker..
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=49d6006e566a6d95
dashboard link: https://syzkaller.appspot.com/bug?extid=227dbc9afd022922d624
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44

Note: no patches were applied.