Re: [syzbot] [dri?] divide error in drm_mode_debug_printmodeline

From: syzbot
Date: Wed Nov 15 2023 - 23:02:12 EST


Hello,

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

gured (established 65536 bind 65536)
[ 4.698580][ T1] MPTCP token hash table entries: 8192 (order: 7, 720896 bytes, vmalloc)
[ 4.706186][ T1] UDP hash table entries: 4096 (order: 7, 655360 bytes, vmalloc)
[ 4.712412][ T1] UDP-Lite hash table entries: 4096 (order: 7, 655360 bytes, vmalloc)
[ 4.716658][ T1] NET: Registered PF_UNIX/PF_LOCAL protocol family
[ 4.722357][ T1] RPC: Registered named UNIX socket transport module.
[ 4.724212][ T1] RPC: Registered udp transport module.
[ 4.725069][ T1] RPC: Registered tcp transport module.
[ 4.727091][ T1] RPC: Registered tcp-with-tls transport module.
[ 4.729048][ T1] RPC: Registered tcp NFSv4.1 backchannel transport module.
[ 4.737515][ T1] NET: Registered PF_XDP protocol family
[ 4.739697][ T1] pci_bus 0000:00: resource 4 [io 0x0000-0x0cf7 window]
[ 4.741876][ T1] pci_bus 0000:00: resource 5 [io 0x0d00-0xffff window]
[ 4.743898][ T1] pci_bus 0000:00: resource 6 [mem 0x000a0000-0x000bffff window]
[ 4.745227][ T1] pci_bus 0000:00: resource 7 [mem 0xc0000000-0xfebfefff window]
[ 4.748706][ T1] pci 0000:00:00.0: Limiting direct PCI/PCI transfers
[ 4.750117][ T1] PCI: CLS 0 bytes, default 64
[ 4.759463][ T1] PCI-DMA: Using software bounce buffering for IO (SWIOTLB)
[ 4.761040][ T1] software IO TLB: mapped [mem 0x00000000b5800000-0x00000000b9800000] (64MB)
[ 4.762515][ T1] ACPI: bus type thunderbolt registered
[ 4.770381][ T60] kworker/u4:2 (60) used greatest stack depth: 26296 bytes left
[ 4.773156][ T1] RAPL PMU: API unit is 2^-32 Joules, 0 fixed counters, 10737418240 ms ovfl timer
[ 4.798952][ T1] kvm_amd: CPU 0 isn't AMD or Hygon
[ 4.800516][ T1] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x1fb6cbb9648, max_idle_ns: 440795209148 ns
[ 4.802622][ T1] clocksource: Switched to clocksource tsc
[ 4.834894][ T74] kworker/u4:4 (74) used greatest stack depth: 25160 bytes left
[ 6.218409][ T1] Initialise system trusted keyrings
[ 6.225315][ T1] workingset: timestamp_bits=40 max_order=21 bucket_order=0
[ 6.234279][ T1] DLM installed
[ 6.238005][ T1] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[ 6.244851][ T1] NFS: Registering the id_resolver key type
[ 6.246129][ T1] Key type id_resolver registered
[ 6.247316][ T1] Key type id_legacy registered
[ 6.248729][ T1] nfs4filelayout_init: NFSv4 File Layout Driver Registering...
[ 6.250443][ T1] nfs4flexfilelayout_init: NFSv4 Flexfile Layout Driver Registering...
[ 6.258315][ T1] Key type cifs.spnego registered
[ 6.259636][ T1] Key type cifs.idmap registered
[ 6.260830][ T1] ntfs: driver 2.1.32 [Flags: R/W].
[ 6.261994][ T1] ntfs3: Max link count 4000
[ 6.262684][ T1] ntfs3: Enabled Linux POSIX ACLs support
[ 6.263806][ T1] ntfs3: Read-only LZX/Xpress compression included
[ 6.265613][ T1] efs: 1.0a - http://aeschi.ch.eu.org/efs/
[ 6.268103][ T1] jffs2: version 2.2. (NAND) (SUMMARY) © 2001-2006 Red Hat, Inc.
[ 6.271702][ T1] romfs: ROMFS MTD (C) 2007 Red Hat, Inc.
[ 6.273229][ T1] QNX4 filesystem 0.2.3 registered.
[ 6.275322][ T1] qnx6: QNX6 filesystem 1.0.0 registered.
[ 6.277012][ T1] fuse: init (API version 7.39)
[ 6.281606][ T1] orangefs_debugfs_init: called with debug mask: :none: :0:
[ 6.284051][ T1] orangefs_init: module version upstream loaded
[ 6.285490][ T1] JFS: nTxBlock = 8192, nTxLock = 65536
[ 6.313750][ T1] SGI XFS with ACLs, security attributes, realtime, quota, no debug enabled
[ 6.319015][ T1] 9p: Installing v9fs 9p2000 file system support
[ 6.320322][ T1] NILFS version 2 loaded
[ 6.321452][ T1] befs: version: 0.9.3
[ 6.322601][ T1] ocfs2: Registered cluster interface o2cb
[ 6.324174][ T1] ocfs2: Registered cluster interface user
[ 6.325892][ T1] OCFS2 User DLM kernel interface loaded
[ 6.341871][ T1] gfs2: GFS2 installed
[ 6.353461][ T1] ceph: loaded (mds proto 32)
[ 6.379550][ T1] NET: Registered PF_ALG protocol family
[ 6.381038][ T1] xor: automatically using best checksumming function avx
[ 6.382602][ T1] async_tx: api initialized (async)
[ 6.383352][ T1] Key type asymmetric registered
[ 6.384356][ T1] Asymmetric key parser 'x509' registered
[ 6.385383][ T1] Asymmetric key parser 'pkcs8' registered
[ 6.386451][ T1] Key type pkcs7_test registered
[ 6.387489][ T1] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 239)
[ 6.389957][ T1] io scheduler mq-deadline registered
[ 6.390822][ T1] io scheduler kyber registered
[ 6.391899][ T1] io scheduler bfq registered
[ 6.402210][ T1] input: Power Button as /devices/LNXSYSTM:00/LNXPWRBN:00/input/input0
[ 6.416990][ T1] ACPI: button: Power Button [PWRF]
[ 6.420110][ T1] input: Sleep Button as /devices/LNXSYSTM:00/LNXSLPBN:00/input/input1
[ 6.423549][ T1] ACPI: button: Sleep Button [SLPF]
[ 6.437563][ T1] ioatdma: Intel(R) QuickData Technology Driver 5.00
[ 6.464441][ T1] ACPI: \_SB_.LNKC: Enabled at IRQ 11
[ 6.467125][ T1] virtio-pci 0000:00:03.0: virtio_pci: leaving for legacy driver
[ 6.493366][ T1] ACPI: \_SB_.LNKD: Enabled at IRQ 10
[ 6.494395][ T1] virtio-pci 0000:00:04.0: virtio_pci: leaving for legacy driver
[ 6.520948][ T1] ACPI: \_SB_.LNKB: Enabled at IRQ 10
[ 6.522290][ T1] virtio-pci 0000:00:06.0: virtio_pci: leaving for legacy driver
[ 6.542518][ T1] virtio-pci 0000:00:07.0: virtio_pci: leaving for legacy driver
[ 6.681895][ T276] kworker/u4:4 (276) used greatest stack depth: 25000 bytes left
[ 7.183861][ T1] N_HDLC line discipline registered with maxframe=4096
[ 7.185565][ T1] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
[ 7.191098][ T1] 00:03: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A
[ 7.206122][ T1] 00:04: ttyS1 at I/O 0x2f8 (irq = 3, base_baud = 115200) is a 16550A
[ 7.222125][ T1] 00:05: ttyS2 at I/O 0x3e8 (irq = 6, base_baud = 115200) is a 16550A
[ 7.234572][ T1] 00:06: ttyS3 at I/O 0x2e8 (irq = 7, base_baud = 115200) is a 16550A
[ 7.262180][ T1] Non-volatile memory driver v1.3
[ 7.282424][ T1] Linux agpgart interface v0.103
[ 7.296450][ T1] ACPI: bus type drm_connector registered
[ 7.307285][ T1] [drm] Initialized vgem 1.0.0 20120112 for vgem on minor 0
[ 7.319716][ T1] [drm] Initialized vkms 1.0.0 20180514 for vkms on minor 1
[ 7.323524][ T1] general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
[ 7.325256][ T1] KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
[ 7.325646][ T1] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.7.0-rc1-syzkaller-00019-gc42d9eeef8e5-dirty #0
[ 7.325646][ T1] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
[ 7.325646][ T1] RIP: 0010:drm_mode_vrefresh+0x9e/0x360
[ 7.325646][ T1] Code: e8 d7 d9 65 fc 45 85 f6 74 73 4c 89 e0 48 c1 e8 03 42 0f b6 04 28 84 c0 0f 85 f8 01 00 00 41 8b 04 24 89 44 24 04 44 0f af f5 <41> 0f b6 45 00 84 c0 0f 85 fd 01 00 00 44 89 34 25 00 00 00 00 4d
[ 7.325646][ T1] RSP: 0000:ffffc90000067050 EFLAGS: 00010202
[ 7.325646][ T1] RAX: 0000000000007b0c RBX: 0000000000000000 RCX: ffff888141668000
[ 7.325646][ T1] RDX: ffff888141668000 RSI: 00000000000001bd RDI: 0000000000000000
[ 7.325646][ T1] RBP: 0000000000000340 R08: ffffffff8528eb99 R09: 0000000000000000
[ 7.325646][ T1] R10: ffffc90000067060 R11: fffff5200000ce0f R12: ffffffff8bce3120
[ 7.325646][ T1] R13: dffffc0000000000 R14: 000000000005a640 R15: ffffffff8bce312e
[ 7.325646][ T1] FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
[ 7.325646][ T1] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 7.325646][ T1] CR2: ffff88823ffff000 CR3: 000000000d730000 CR4: 00000000003506f0
[ 7.325646][ T1] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 7.325646][ T1] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 7.325646][ T1] Call Trace:
[ 7.325646][ T1] <TASK>
[ 7.325646][ T1] ? __die_body+0x8b/0xe0
[ 7.325646][ T1] ? die_addr+0xc9/0x100
[ 7.325646][ T1] ? exc_general_protection+0x3c2/0x5b0
[ 7.325646][ T1] ? asm_exc_general_protection+0x26/0x30
[ 7.325646][ T1] ? drm_mode_vrefresh+0x79/0x360
[ 7.325646][ T1] ? drm_mode_vrefresh+0x9e/0x360
[ 7.325646][ T1] drm_add_modes_noedid+0xb5/0x230
[ 7.325646][ T1] vkms_conn_get_modes+0x20/0x40
[ 7.325646][ T1] drm_helper_probe_single_connector_modes+0x7d9/0x11f0
[ 7.325646][ T1] ? drm_helper_probe_detect+0x4e0/0x4e0
[ 7.325646][ T1] ? drm_client_modeset_probe+0x32c/0x4790
[ 7.325646][ T1] ? rcu_is_watching+0x15/0xb0
[ 7.325646][ T1] ? __kmalloc+0xe6/0x230
[ 7.325646][ T1] ? drm_connector_list_iter_end+0xb5/0xd0
[ 7.325646][ T1] drm_client_modeset_probe+0x433/0x4790
[ 7.325646][ T1] ? verify_lock_unused+0x140/0x140
[ 7.325646][ T1] ? _raw_spin_unlock_irqrestore+0x8f/0x140
[ 7.325646][ T1] ? lockdep_hardirqs_on+0x98/0x140
[ 7.325646][ T1] ? drm_client_modeset_release+0x300/0x300
[ 7.325646][ T1] ? __mutex_trylock_common+0x182/0x2e0
[ 7.325646][ T1] ? __might_sleep+0xc0/0xc0
[ 7.325646][ T1] ? trace_raw_output_contention_end+0xd0/0xd0
[ 7.325646][ T1] ? __mutex_trylock_common+0x182/0x2e0
[ 7.325646][ T1] __drm_fb_helper_initial_config_and_unlock+0x112/0x1e20
[ 7.325646][ T1] ? __mutex_lock+0x2ee/0xd60
[ 7.325646][ T1] ? rcu_is_watching+0x15/0xb0
[ 7.325646][ T1] ? trace_contention_end+0x3c/0xf0
[ 7.325646][ T1] ? __mutex_lock+0x2ee/0xd60
[ 7.325646][ T1] ? drm_fb_helper_initial_config+0x35/0x50
[ 7.325646][ T1] ? drm_fb_helper_initial_config+0x50/0x50
[ 7.325646][ T1] ? drm_client_register+0x4e/0x210
[ 7.325646][ T1] ? mutex_lock_nested+0x20/0x20
[ 7.325646][ T1] ? drm_prime_init_file_private+0x39/0x40
[ 7.325646][ T1] drm_fbdev_generic_client_hotplug+0x166/0x210
[ 7.325646][ T1] drm_client_register+0x17e/0x210
[ 7.325646][ T1] vkms_init+0x5f1/0x730
[ 7.325646][ T1] ? vgem_init+0x290/0x290
[ 7.325646][ T1] ? vgem_init+0x290/0x290
[ 7.325646][ T1] do_one_initcall+0x234/0x800
[ 7.325646][ T1] ? vgem_init+0x290/0x290
[ 7.325646][ T1] ? IS_ERR_OR_NULL+0x20/0x20
[ 7.325646][ T1] ? lockdep_hardirqs_on_prepare+0x43c/0x7a0
[ 7.325646][ T1] ? parameq+0x220/0x220
[ 7.325646][ T1] ? slab_post_alloc_hook+0x6c/0x3c0
[ 7.325646][ T1] ? do_initcalls+0x1c/0x80
[ 7.325646][ T1] ? rcu_is_watching+0x15/0xb0
[ 7.325646][ T1] do_initcall_level+0x157/0x210
[ 7.325646][ T1] do_initcalls+0x3f/0x80
[ 7.325646][ T1] kernel_init_freeable+0x429/0x5c0
[ 7.325646][ T1] ? obsolete_checksetup+0x200/0x200
[ 7.325646][ T1] ? print_irqtrace_events+0x220/0x220
[ 7.325646][ T1] ? rest_init+0x300/0x300
[ 7.325646][ T1] ? rest_init+0x300/0x300
[ 7.325646][ T1] ? rest_init+0x300/0x300
[ 7.325646][ T1] kernel_init+0x1d/0x2a0
[ 7.325646][ T1] ret_from_fork+0x48/0x80
[ 7.325646][ T1] ? rest_init+0x300/0x300
[ 7.325646][ T1] ret_from_fork_asm+0x11/0x20
[ 7.325646][ T1] </TASK>
[ 7.325646][ T1] Modules linked in:
[ 7.439276][ T1] ---[ end trace 0000000000000000 ]---
[ 7.440497][ T1] RIP: 0010:drm_mode_vrefresh+0x9e/0x360
[ 7.441446][ T1] Code: e8 d7 d9 65 fc 45 85 f6 74 73 4c 89 e0 48 c1 e8 03 42 0f b6 04 28 84 c0 0f 85 f8 01 00 00 41 8b 04 24 89 44 24 04 44 0f af f5 <41> 0f b6 45 00 84 c0 0f 85 fd 01 00 00 44 89 34 25 00 00 00 00 4d
[ 7.444309][ T1] RSP: 0000:ffffc90000067050 EFLAGS: 00010202
[ 7.445225][ T1] RAX: 0000000000007b0c RBX: 0000000000000000 RCX: ffff888141668000
[ 7.446748][ T1] RDX: ffff888141668000 RSI: 00000000000001bd RDI: 0000000000000000
[ 7.448285][ T1] RBP: 0000000000000340 R08: ffffffff8528eb99 R09: 0000000000000000
[ 7.450542][ T1] R10: ffffc90000067060 R11: fffff5200000ce0f R12: ffffffff8bce3120
[ 7.451988][ T1] R13: dffffc0000000000 R14: 000000000005a640 R15: ffffffff8bce312e
[ 7.453626][ T1] FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
[ 7.454940][ T1] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 7.456230][ T1] CR2: ffff88823ffff000 CR3: 000000000d730000 CR4: 00000000003506f0
[ 7.457734][ T1] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 7.459189][ T1] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 7.460386][ T1] Kernel panic - not syncing: Fatal exception
[ 7.461513][ T1] Kernel Offset: disabled
[ 7.462264][ T1] Rebooting in 86400 seconds..


syzkaller build log:
go env (err=<nil>)
GO111MODULE="auto"
GOARCH="amd64"
GOBIN=""
GOCACHE="/syzkaller/.cache/go-build"
GOENV="/syzkaller/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
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"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.20.1"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/syzkaller/jobs-2/linux/gopath/src/github.com/google/syzkaller/go.mod"
GOWORK=""
CGO_CFLAGS="-O2 -g"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-O2 -g"
CGO_FFLAGS="-O2 -g"
CGO_LDFLAGS="-O2 -g"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build76428843=/tmp/go-build -gno-record-gcc-switches"

git status (err=<nil>)
HEAD detached at 6d6dbf8ab
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:32: run command via tools/syz-env for best compatibility, see:
Makefile:33: https://github.com/google/syzkaller/blob/master/docs/contributing.md#using-syz-env
go list -f '{{.Stale}}' ./sys/syz-sysgen | grep -q false || go install ./sys/syz-sysgen
make .descriptions
tput: No value for $TERM and no -T specified
tput: No value for $TERM and no -T specified
bin/syz-sysgen
touch .descriptions
GOOS=linux GOARCH=amd64 go build "-ldflags=-s -w -X github.com/google/syzkaller/prog.GitRevision=6d6dbf8ab21a52df701946afac2a86f93a88fdc8 -X 'github.com/google/syzkaller/prog.gitRevisionDate=20231111-003831'" "-tags=syz_target syz_os_linux syz_arch_amd64 " -o ./bin/linux_amd64/syz-fuzzer github.com/google/syzkaller/syz-fuzzer
GOOS=linux GOARCH=amd64 go build "-ldflags=-s -w -X github.com/google/syzkaller/prog.GitRevision=6d6dbf8ab21a52df701946afac2a86f93a88fdc8 -X 'github.com/google/syzkaller/prog.gitRevisionDate=20231111-003831'" "-tags=syz_target syz_os_linux syz_arch_amd64 " -o ./bin/linux_amd64/syz-execprog github.com/google/syzkaller/tools/syz-execprog
GOOS=linux GOARCH=amd64 go build "-ldflags=-s -w -X github.com/google/syzkaller/prog.GitRevision=6d6dbf8ab21a52df701946afac2a86f93a88fdc8 -X 'github.com/google/syzkaller/prog.gitRevisionDate=20231111-003831'" "-tags=syz_target syz_os_linux syz_arch_amd64 " -o ./bin/linux_amd64/syz-stress github.com/google/syzkaller/tools/syz-stress
mkdir -p ./bin/linux_amd64
gcc -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 -fpermissive -w -DGOOS_linux=1 -DGOARCH_amd64=1 \
-DHOSTGOOS_linux=1 -DGIT_REVISION=\"6d6dbf8ab21a52df701946afac2a86f93a88fdc8\"


Error text is too large and was truncated, full error text is at:
https://syzkaller.appspot.com/x/error.txt?x=1266c2b8e80000


Tested on:

commit: c42d9eee Merge tag 'hardening-v6.7-rc2' of git://git.k..
git tree: upstream
kernel config: https://syzkaller.appspot.com/x/.config?x=b5bf1661f609e7f0
dashboard link: https://syzkaller.appspot.com/bug?extid=2e93e6fb36e6fdc56574
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch: https://syzkaller.appspot.com/x/patch.diff?x=1459d067680000