Re: [syzbot] [kvm-x86?] KASAN: use-after-free Read in kvm_setup_guest_pvclock

[syzbot <syzbot+fb7c2dd166d3ea63df2a@syzkaller.appspotmail.com>]

Hello,

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

0000b4600000-0x00000000b8600000] (64MB)
[    6.255166][    T1] ACPI: bus type thunderbolt registered
[    6.306362][    T1] RAPL PMU: API unit is 2^-32 Joules, 0 fixed counters, 10737418240 ms ovfl timer
[    6.320726][   T70] kworker/u8:4 (70) used greatest stack depth: 27600 bytes left
[    6.392355][    T1] kvm_amd: CPU 0 isn't AMD or Hygon
[    6.392394][    T1] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x1fb63109b96, max_idle_ns: 440795265316 ns
[    6.393087][    T1] clocksource: Switched to clocksource tsc
[    6.393213][   T71] kworker/u8:3 (71) used greatest stack depth: 27344 bytes left
[    6.418119][   T75] kworker/u8:4 (75) used greatest stack depth: 27200 bytes left
[    6.516097][    T1] Initialise system trusted keyrings
[    6.532538][    T1] workingset: timestamp_bits=40 (anon: 35) max_order=21 bucket_order=0 (anon: 0)
[    6.566694][    T1] DLM installed
[    6.592800][    T1] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[    6.625574][    T1] NFS: Registering the id_resolver key type
[    6.625765][    T1] Key type id_resolver registered
[    6.625780][    T1] Key type id_legacy registered
[    6.626561][    T1] nfs4filelayout_init: NFSv4 File Layout Driver Registering...
[    6.626840][    T1] nfs4flexfilelayout_init: NFSv4 Flexfile Layout Driver Registering...
[    6.683834][    T1] smbdirect: subsystem loading...
[    6.716365][    T1] smbdirect: subsystem loaded
[    6.763512][    T1] Key type cifs.spnego registered
[    6.764174][    T1] Key type cifs.idmap registered
[    6.792353][    T1] ntfs3: Enabled Linux POSIX ACLs support
[    6.792365][    T1] ntfs3: Read-only LZX/Xpress compression included
[    6.792747][    T1] jffs2: version 2.2. (NAND) (SUMMARY)  © 2001-2006 Red Hat, Inc.
[    6.799004][    T1] romfs: ROMFS MTD (C) 2007 Red Hat, Inc.
[    6.851007][    T1] QNX4 filesystem 0.2.3 registered.
[    6.851285][    T1] qnx6: QNX6 filesystem 1.0.0 registered.
[    6.853799][    T1] fuse: init (API version 7.45)
[    6.887403][    T1] orangefs_debugfs_init: called with debug mask: :none: :0:
[    6.894486][    T1] orangefs_init: module version upstream loaded
[    6.898940][    T1] JFS: nTxBlock = 8192, nTxLock = 65536
[    6.932174][    T1] SGI XFS with ACLs, security attributes, realtime, quota, no debug enabled
[    6.955145][    T1] 9p: Installing v9fs 9p2000 file system support
[    6.956070][    T1] NILFS version 2 loaded
[    6.956080][    T1] befs: version: 0.9.3
[    6.957362][    T1] ocfs2: Registered cluster interface o2cb
[    6.999664][    T1] ocfs2: Registered cluster interface user
[    7.020743][    T1] OCFS2 User DLM kernel interface loaded
[    7.067258][    T1] gfs2: GFS2 installed
[    7.097413][    T1] ceph: loaded (mds proto 32)
[    7.117915][    T1] NET: Registered PF_ALG protocol family
[    7.120294][    T1] async_tx: api initialized (async)
[    7.120581][    T1] Key type asymmetric registered
[    7.120754][    T1] Asymmetric key parser 'x509' registered
[    7.120812][    T1] Asymmetric key parser 'pkcs8' registered
[    7.121599][    T1] Key type pkcs7_test registered
[    7.125388][    T1] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 239)
[    7.176102][    T1] io scheduler mq-deadline registered
[    7.176126][    T1] io scheduler kyber registered
[    7.176786][    T1] io scheduler bfq registered
[    7.184322][    T1] raid6: skipped pq benchmark and selected avx2x4
[    7.222671][  T151] kworker/u8:3 (151) used greatest stack depth: 26912 bytes left
[    7.246411][  T156] kworker/u8:5 (156) used greatest stack depth: 26048 bytes left
[    7.267490][    T1] input: Power Button as /devices/platform/LNXPWRBN:00/input/input0
[    7.274296][    T1] ACPI: button: Power Button [PWRF]
[    7.283915][    T1] input: Sleep Button as /devices/platform/LNXSLPBN:00/input/input1
[    7.290898][    T1] ACPI: button: Sleep Button [SLPF]
[    7.344578][    T1] ioatdma: Intel(R) QuickData Technology Driver 5.00
[    7.411368][   T10] ACPI: \_SB_.LNKC: Enabled at IRQ 11
[    7.411566][   T10] virtio-pci 0000:00:03.0: virtio_pci: leaving for legacy driver
[    7.480603][   T10] ACPI: \_SB_.LNKD: Enabled at IRQ 10
[    7.480814][   T10] virtio-pci 0000:00:04.0: virtio_pci: leaving for legacy driver
[    7.540509][   T10] ACPI: \_SB_.LNKB: Enabled at IRQ 10
[    7.540693][   T10] virtio-pci 0000:00:06.0: virtio_pci: leaving for legacy driver
[    7.589579][   T10] virtio-pci 0000:00:07.0: virtio_pci: leaving for legacy driver
[    8.845365][    T1] N_HDLC line discipline registered with maxframe=4096
[    8.848528][    T1] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
[    8.888282][    T1] 00:02: ttyS0 I/O:0x3f8 (irq = 4, base_baud = 115200) is a 16550A
[    8.932129][    T1] 00:03: ttyS1 I/O:0x2f8 (irq = 3, base_baud = 115200) is a 16550A
[    8.975973][    T1] 00:04: ttyS2 I/O:0x3e8 (irq = 6, base_baud = 115200) is a 16550A
[    9.048379][    T1] 00:05: ttyS3 I/O:0x2e8 (irq = 7, base_baud = 115200) is a 16550A
[    9.136987][    T1] Non-volatile memory driver v1.3
[    9.209627][    T1] usbcore: registered new interface driver xillyusb
[    9.232020][    T1] ACPI: bus type drm_connector registered
[    9.265590][    T1] [drm] Initialized vgem 1.0.0 for vgem on minor 0
[    9.287444][    T1] ------------[ cut here ]------------
[    9.287465][    T1] [PLANE:35:plane-0] pixel format with alpha exposed but blend mode not setup
[    9.287490][    T1] WARNING: drivers/gpu/drm/drm_mode_config.c:873 at drm_mode_config_validate+0x1c6d/0x1e60, CPU#1: swapper/0/1
[    9.287615][    T1] Modules linked in:
[    9.287649][    T1] CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
[    9.287667][    T1] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
[    9.287727][    T1] RIP: 0010:drm_mode_config_validate+0x1cae/0x1e60
[    9.287763][    T1] Code: 0f 85 ae 00 00 00 4d 8d 77 10 8b 6d 00 4c 89 f0 48 c1 e8 03 80 3c 18 00 74 08 4c 89 f7 e8 fa b0 be fc 49 8b 16 4c 89 ef 89 ee <67> 48 0f b9 3a eb 05 e8 d6 55 52 fc 49 bd 00 00 00 00 00 fc ff df
[    9.287786][    T1] RSP: 0000:ffffc90000067810 EFLAGS: 00010246
[    9.287807][    T1] RAX: 1ffff11004d00408 RBX: dffffc0000000000 RCX: ffff88801c6e5d00
[    9.287824][    T1] RDX: ffff8880263f9dc0 RSI: 0000000000000023 RDI: ffffffff8fd964c0
[    9.287840][    T1] RBP: 0000000000000023 R08: 0000000000000000 R09: 0000000000000000
[    9.287854][    T1] R10: dffffc0000000000 R11: fffffbfff1f9c610 R12: dffffc0000000000
[    9.287871][    T1] R13: ffffffff8fd964c0 R14: ffff888026802040 R15: ffff888026802030
[    9.287888][    T1] FS:  0000000000000000(0000) GS:ffff888125b69000(0000) knlGS:0000000000000000
[    9.287906][    T1] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    9.287923][    T1] CR2: 0000000000000000 CR3: 000000000e1b0000 CR4: 00000000003526f0
[    9.287942][    T1] Call Trace:
[    9.287957][    T1]  <TASK>
[    9.287982][    T1]  ? debugfs_create_file_full+0x3f/0x60
[    9.288026][    T1]  drm_dev_register+0x7f/0xd80
[    9.288197][    T1]  vkms_create+0x40d/0x4f0
[    9.288232][    T1]  ? __pfx_vkms_init+0x10/0x10
[    9.288272][    T1]  vkms_init+0x57/0x80
[    9.288307][    T1]  do_one_initcall+0x250/0x870
[    9.288334][    T1]  ? __pfx_vkms_init+0x10/0x10
[    9.288371][    T1]  ? __pfx_do_one_initcall+0x10/0x10
[    9.288396][    T1]  ? ktime_get+0x1f5/0x220
[    9.288430][    T1]  ? clockevents_program_event+0x491/0x630
[    9.288459][    T1]  ? __pfx___schedule+0x10/0x10
[    9.288513][    T1]  ? irqentry_exit+0x218/0x8f0
[    9.288544][    T1]  ? lockdep_hardirqs_on+0x7a/0x110
[    9.288579][    T1]  ? irqentry_exit+0x218/0x8f0
[    9.288612][    T1]  ? trace_irq_disable+0x3b/0x140
[    9.288664][    T1]  ? next_arg+0x4a0/0x5e0
[    9.288690][    T1]  ? parameq+0x14d/0x170
[    9.288724][    T1]  ? parse_args+0x9c3/0xad0
[    9.288771][    T1]  ? trace_kmalloc+0x2a/0xf0
[    9.288803][    T1]  ? rcu_is_watching+0x15/0xb0
[    9.288831][    T1]  do_initcall_level+0x10a/0x1a0
[    9.288860][    T1]  ? kernel_init+0x22/0x1d0
[    9.288886][    T1]  do_initcalls+0x59/0xa0
[    9.288913][    T1]  kernel_init_freeable+0x29d/0x3e0
[    9.288939][    T1]  ? __pfx_kernel_init+0x10/0x10
[    9.288967][    T1]  kernel_init+0x22/0x1d0
[    9.288993][    T1]  ? __pfx_kernel_init+0x10/0x10
[    9.289018][    T1]  ret_from_fork+0x514/0xb70
[    9.289072][    T1]  ? __pfx_ret_from_fork+0x10/0x10
[    9.289099][    T1]  ? __switch_to+0xc89/0x1420
[    9.289217][    T1]  ? __pfx_kernel_init+0x10/0x10
[    9.289246][    T1]  ret_from_fork_asm+0x1a/0x30
[    9.289296][    T1]  </TASK>
[    9.289319][    T1] Kernel panic - not syncing: kernel: panic_on_warn set ...
[    9.289336][    T1] CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
[    9.289363][    T1] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
[    9.289376][    T1] Call Trace:
[    9.289394][    T1]  <TASK>
[    9.289403][    T1]  vpanic+0x56c/0xa60
[    9.289437][    T1]  ? __pfx__printk+0x10/0x10
[    9.289460][    T1]  ? __pfx_vpanic+0x10/0x10
[    9.289491][    T1]  ? is_bpf_text_address+0x292/0x2b0
[    9.289513][    T1]  ? is_bpf_text_address+0x26/0x2b0
[    9.289541][    T1]  panic+0xc5/0xd0
[    9.289574][    T1]  ? __pfx_panic+0x10/0x10
[    9.289615][    T1]  ? ret_from_fork_asm+0x1a/0x30
[    9.289646][    T1]  __warn+0x315/0x4c0
[    9.289676][    T1]  ? drm_mode_config_validate+0x1c6d/0x1e60
[    9.289707][    T1]  ? drm_mode_config_validate+0x1c6d/0x1e60
[    9.289735][    T1]  __report_bug+0x276/0x570
[    9.289773][    T1]  ? drm_mode_config_validate+0x1c6d/0x1e60
[    9.289802][    T1]  ? __pfx___report_bug+0x10/0x10
[    9.289844][    T1]  ? _raw_spin_unlock_irqrestore+0x30/0x80
[    9.289879][    T1]  ? lockdep_hardirqs_on+0x7a/0x110
[    9.289914][    T1]  ? rt_mutex_slowunlock+0x4ee/0xa20
[    9.289945][    T1]  report_bug_entry+0x19a/0x290
[    9.289981][    T1]  ? drm_mode_config_validate+0x1cae/0x1e60
[    9.290008][    T1]  ? drm_mode_config_validate+0x1cb3/0x1e60
[    9.290042][    T1]  handle_bug+0xce/0x200
[    9.290067][    T1]  exc_invalid_op+0x1a/0x50
[    9.290090][    T1]  asm_exc_invalid_op+0x1a/0x20
[    9.290113][    T1] RIP: 0010:drm_mode_config_validate+0x1cae/0x1e60
[    9.290142][    T1] Code: 0f 85 ae 00 00 00 4d 8d 77 10 8b 6d 00 4c 89 f0 48 c1 e8 03 80 3c 18 00 74 08 4c 89 f7 e8 fa b0 be fc 49 8b 16 4c 89 ef 89 ee <67> 48 0f b9 3a eb 05 e8 d6 55 52 fc 49 bd 00 00 00 00 00 fc ff df
[    9.290161][    T1] RSP: 0000:ffffc90000067810 EFLAGS: 00010246
[    9.290181][    T1] RAX: 1ffff11004d00408 RBX: dffffc0000000000 RCX: ffff88801c6e5d00
[    9.290198][    T1] RDX: ffff8880263f9dc0 RSI: 0000000000000023 RDI: ffffffff8fd964c0
[    9.290213][    T1] RBP: 0000000000000023 R08: 0000000000000000 R09: 0000000000000000
[    9.290226][    T1] R10: dffffc0000000000 R11: fffffbfff1f9c610 R12: dffffc0000000000
[    9.290242][    T1] R13: ffffffff8fd964c0 R14: ffff888026802040 R15: ffff888026802030
[    9.290303][    T1]  ? debugfs_create_file_full+0x3f/0x60
[    9.290342][    T1]  drm_dev_register+0x7f/0xd80
[    9.290372][    T1]  vkms_create+0x40d/0x4f0
[    9.290405][    T1]  ? __pfx_vkms_init+0x10/0x10
[    9.290438][    T1]  vkms_init+0x57/0x80
[    9.290473][    T1]  do_one_initcall+0x250/0x870
[    9.290498][    T1]  ? __pfx_vkms_init+0x10/0x10
[    9.290532][    T1]  ? __pfx_do_one_initcall+0x10/0x10
[    9.290654][    T1]  ? ktime_get+0x1f5/0x220
[    9.290683][    T1]  ? clockevents_program_event+0x491/0x630
[    9.290707][    T1]  ? __pfx___schedule+0x10/0x10
[    9.290745][    T1]  ? irqentry_exit+0x218/0x8f0
[    9.290776][    T1]  ? lockdep_hardirqs_on+0x7a/0x110
[    9.290811][    T1]  ? irqentry_exit+0x218/0x8f0
[    9.290843][    T1]  ? trace_irq_disable+0x3b/0x140
[    9.290894][    T1]  ? next_arg+0x4a0/0x5e0
[    9.290917][    T1]  ? parameq+0x14d/0x170
[    9.290951][    T1]  ? parse_args+0x9c3/0xad0
[    9.290998][    T1]  ? trace_kmalloc+0x2a/0xf0
[    9.291070][    T1]  ? rcu_is_watching+0x15/0xb0
[    9.291100][    T1]  do_initcall_level+0x10a/0x1a0
[    9.291288][    T1]  ? kernel_init+0x22/0x1d0
[    9.291320][    T1]  do_initcalls+0x59/0xa0
[    9.291359][    T1]  kernel_init_freeable+0x29d/0x3e0
[    9.291388][    T1]  ? __pfx_kernel_init+0x10/0x10
[    9.291419][    T1]  kernel_init+0x22/0x1d0
[    9.291446][    T1]  ? __pfx_kernel_init+0x10/0x10
[    9.291482][    T1]  ret_from_fork+0x514/0xb70
[    9.291516][    T1]  ? __pfx_ret_from_fork+0x10/0x10
[    9.291545][    T1]  ? __switch_to+0xc89/0x1420
[    9.291569][    T1]  ? __pfx_kernel_init+0x10/0x10
[    9.291596][    T1]  ret_from_fork_asm+0x1a/0x30
[    9.291636][    T1]  </TASK>
[    9.291899][    T1] Kernel Offset: disabled


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-build721356953=/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 00e8b0fd0d
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=00e8b0fd0d17bb06fe23c0e743356351ada78c22 -X github.com/google/syzkaller/prog.gitRevisionDate=20260630-130833"  ./sys/syz-sysgen | grep -q false || go install -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=00e8b0fd0d17bb06fe23c0e743356351ada78c22 -X github.com/google/syzkaller/prog.gitRevisionDate=20260630-130833"  ./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=00e8b0fd0d17bb06fe23c0e743356351ada78c22 -X github.com/google/syzkaller/prog.gitRevisionDate=20260630-130833"  -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=\"00e8b0fd0d17bb06fe23c0e743356351ada78c22\"
/usr/bin/ld: /tmp/ccMCDxTH.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=124c32b9580000


Tested on:

commit:         0718283a Add linux-next specific files for 20260717
git tree:       linux-next
kernel config:  https://syzkaller.appspot.com/x/.config?x=c45dee6227f09fbb
dashboard link: https://syzkaller.appspot.com/bug?extid=fb7c2dd166d3ea63df2a
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15f362b9580000