Re: [syzbot] [exfat?] [ocfs2?] kernel BUG in link_path_walk

[syzbot <syzbot+d222f4b7129379c3d5bc@syzkaller.appspotmail.com>]

Hello,

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

SYZFAIL: failed to recv rpc

SYZFAIL: failed to recv rpc


Warning: Permanently added '10.128.0.177' (ED25519) to the list of known hosts.
2025/12/04 10:11:47 parsed 1 programs
[   78.910789][ T5830] cgroup: Unknown subsys name 'net'
[   79.061524][ T5830] cgroup: Unknown subsys name 'cpuset'
[   79.071037][ T5830] cgroup: Unknown subsys name 'rlimit'
Setting up swapspace version 1, size = 127995904 bytes
[   80.470098][ T5830] Adding 124996k swap on ./swap-file.  Priority:0 extents:1 across:124996k 
[   83.462586][ T5842] soft_limit_in_bytes is deprecated and will be removed. Please report your usecase to linux-mm@kvack.org if you depend on this functionality.
[   83.768296][ T1303] wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[   83.776268][ T1303] wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50
[   84.018160][   T36] wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[   84.026332][   T36] wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
[   84.079691][ T5149] Bluetooth: hci0: unexpected cc 0x0c03 length: 249 > 1
[   84.089721][ T5149] Bluetooth: hci0: unexpected cc 0x1003 length: 249 > 9
[   84.097886][ T5149] Bluetooth: hci0: unexpected cc 0x1001 length: 249 > 9
[   84.120020][ T5149] Bluetooth: hci0: unexpected cc 0x0c23 length: 249 > 4
[   84.128054][ T5149] Bluetooth: hci0: unexpected cc 0x0c38 length: 249 > 2
[   86.764273][ T5914] chnl_net:caif_netlink_parms(): no params data found
[   86.952176][   T10] cfg80211: failed to load regulatory.db
[   86.970822][ T5914] bridge0: port 1(bridge_slave_0) entered blocking state
[   86.987663][ T5914] bridge0: port 1(bridge_slave_0) entered disabled state
[   86.995387][ T5914] bridge_slave_0: entered allmulticast mode
[   87.004680][ T5914] bridge_slave_0: entered promiscuous mode
[   87.019597][ T5914] bridge0: port 2(bridge_slave_1) entered blocking state
[   87.038879][ T5914] bridge0: port 2(bridge_slave_1) entered disabled state
[   87.046589][ T5914] bridge_slave_1: entered allmulticast mode
[   87.055691][ T5914] bridge_slave_1: entered promiscuous mode
[   87.132629][ T5914] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
[   87.165237][ T5914] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link
[   87.263236][ T5914] team0: Port device team_slave_0 added
[   87.273397][ T5914] team0: Port device team_slave_1 added
[   87.303206][ T5914] batman_adv: batadv0: Adding interface: batadv_slave_0
[   87.311015][ T5914] batman_adv: batadv0: The MTU of interface batadv_slave_0 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1532 would solve the problem.
[   87.339107][ T5914] batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active
[   87.352524][ T5914] batman_adv: batadv0: Adding interface: batadv_slave_1
[   87.360592][ T5914] batman_adv: batadv0: The MTU of interface batadv_slave_1 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1532 would solve the problem.
[   87.387771][ T5914] batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
[   87.429283][ T5914] hsr_slave_0: entered promiscuous mode
[   87.436383][ T5914] hsr_slave_1: entered promiscuous mode
[   87.589866][ T5914] netdevsim netdevsim2 netdevsim0: renamed from eth0
[   87.602532][ T5914] netdevsim netdevsim2 netdevsim1: renamed from eth1
[   87.612793][ T5914] netdevsim netdevsim2 netdevsim2: renamed from eth2
[   87.624712][ T5914] netdevsim netdevsim2 netdevsim3: renamed from eth3
[   87.702119][ T5914] 8021q: adding VLAN 0 to HW filter on device bond0
[   87.727060][ T5914] 8021q: adding VLAN 0 to HW filter on device team0
[   87.742924][ T3460] bridge0: port 1(bridge_slave_0) entered blocking state
[   87.750338][ T3460] bridge0: port 1(bridge_slave_0) entered forwarding state
[   87.767840][   T13] bridge0: port 2(bridge_slave_1) entered blocking state
[   87.775679][   T13] bridge0: port 2(bridge_slave_1) entered forwarding state
[   87.951069][ T5914] 8021q: adding VLAN 0 to HW filter on device batadv0
[   87.997784][ T5914] veth0_vlan: entered promiscuous mode
[   88.011677][ T5914] veth1_vlan: entered promiscuous mode
[   88.040488][ T5914] veth0_macvtap: entered promiscuous mode
[   88.050521][ T5914] veth1_macvtap: entered promiscuous mode
[   88.070672][ T5914] batman_adv: batadv0: Interface activated: batadv_slave_0
[   88.086679][ T5914] batman_adv: batadv0: Interface activated: batadv_slave_1
[   88.102451][ T1303] netdevsim netdevsim2 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
[   88.112929][ T1303] netdevsim netdevsim2 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
[   88.125269][ T1303] netdevsim netdevsim2 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
[   88.138936][ T1303] netdevsim netdevsim2 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
2025/12/04 10:11:58 executed programs: 0
[   88.265933][ T5149] Bluetooth: hci0: unexpected cc 0x0c03 length: 249 > 1
[   88.275000][ T5149] Bluetooth: hci0: unexpected cc 0x1003 length: 249 > 9
[   88.283928][ T5149] Bluetooth: hci0: unexpected cc 0x1001 length: 249 > 9
[   88.294110][ T5149] Bluetooth: hci0: unexpected cc 0x0c23 length: 249 > 4
[   88.303601][ T5149] Bluetooth: hci0: unexpected cc 0x0c38 length: 249 > 2
[   88.516655][ T5945] chnl_net:caif_netlink_parms(): no params data found
[   88.589071][ T5945] bridge0: port 1(bridge_slave_0) entered blocking state
[   88.597183][ T5945] bridge0: port 1(bridge_slave_0) entered disabled state
[   88.605206][ T5945] bridge_slave_0: entered allmulticast mode
[   88.613430][ T5945] bridge_slave_0: entered promiscuous mode
[   88.621792][ T5945] bridge0: port 2(bridge_slave_1) entered blocking state
[   88.629190][ T5945] bridge0: port 2(bridge_slave_1) entered disabled state
[   88.636388][ T5945] bridge_slave_1: entered allmulticast mode
[   88.644502][ T5945] bridge_slave_1: entered promiscuous mode
[   88.679834][ T5945] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
[   88.693258][ T5945] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link
[   88.729876][ T5945] team0: Port device team_slave_0 added
[   88.739741][ T5945] team0: Port device team_slave_1 added
[   88.770447][ T5945] batman_adv: batadv0: Adding interface: batadv_slave_0
[   88.778982][ T5945] batman_adv: batadv0: The MTU of interface batadv_slave_0 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1532 would solve the problem.
[   88.806119][ T5945] batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active
[   88.819400][ T5945] batman_adv: batadv0: Adding interface: batadv_slave_1
[   88.826898][ T5945] batman_adv: batadv0: The MTU of interface batadv_slave_1 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1532 would solve the problem.
[   88.854775][ T5945] batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
[   88.906117][ T5945] hsr_slave_0: entered promiscuous mode
[   88.913653][ T5945] hsr_slave_1: entered promiscuous mode
[   88.920136][ T5945] debugfs: 'hsr0' already exists in 'hsr'
[   88.926073][ T5945] Cannot create hsr debugfs directory
[   89.100742][ T5945] netdevsim netdevsim0 netdevsim0: renamed from eth0
[   89.113003][ T5945] netdevsim netdevsim0 netdevsim1: renamed from eth1
[   89.123282][ T5945] netdevsim netdevsim0 netdevsim2: renamed from eth2
[   89.134611][ T5945] netdevsim netdevsim0 netdevsim3: renamed from eth3
[   89.164880][ T5945] bridge0: port 2(bridge_slave_1) entered blocking state
[   89.172220][ T5945] bridge0: port 2(bridge_slave_1) entered forwarding state
[   89.180595][ T5945] bridge0: port 1(bridge_slave_0) entered blocking state
[   89.188151][ T5945] bridge0: port 1(bridge_slave_0) entered forwarding state
[   89.201467][   T13] bridge0: port 1(bridge_slave_0) entered disabled state
[   89.210194][   T13] bridge0: port 2(bridge_slave_1) entered disabled state
[   89.271133][ T5945] 8021q: adding VLAN 0 to HW filter on device bond0
[   89.292385][ T5945] 8021q: adding VLAN 0 to HW filter on device team0
[   89.304472][   T13] bridge0: port 1(bridge_slave_0) entered blocking state
[   89.311731][   T13] bridge0: port 1(bridge_slave_0) entered forwarding state
[   89.328520][ T1303] bridge0: port 2(bridge_slave_1) entered blocking state
[   89.336026][ T1303] bridge0: port 2(bridge_slave_1) entered forwarding state
[   89.510299][ T5945] 8021q: adding VLAN 0 to HW filter on device batadv0
[   89.555268][ T5945] veth0_vlan: entered promiscuous mode
[   89.567506][ T5945] veth1_vlan: entered promiscuous mode
[   89.602029][ T5945] veth0_macvtap: entered promiscuous mode
[   89.611643][ T5945] veth1_macvtap: entered promiscuous mode
[   89.630992][ T5945] batman_adv: batadv0: Interface activated: batadv_slave_0
[   89.645744][ T5945] batman_adv: batadv0: Interface activated: batadv_slave_1
[   89.661459][   T13] netdevsim netdevsim0 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
[   89.675047][   T13] netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
[   89.685863][   T13] netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
[   89.695952][   T13] netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
[   89.763899][ T3460] wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[   89.773242][ T3460] wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50
[   89.806188][   T13] wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[   89.814827][   T13] wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
SYZFAIL: failed to recv rpc
[   90.239026][   T13] netdevsim netdevsim2 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0


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-build2089224975=/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='go1.24.4'
GOWORK=''
PKG_CONFIG='pkg-config'

git status (err=<nil>)
HEAD detached at d6526ea3e
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=d6526ea3e6ad9081c902859bbb80f9f840377cb4 -X github.com/google/syzkaller/prog.gitRevisionDate=20251126-113115"  ./sys/syz-sysgen | grep -q false || go install -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=d6526ea3e6ad9081c902859bbb80f9f840377cb4 -X github.com/google/syzkaller/prog.gitRevisionDate=20251126-113115"  ./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=d6526ea3e6ad9081c902859bbb80f9f840377cb4 -X github.com/google/syzkaller/prog.gitRevisionDate=20251126-113115"  -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=\"d6526ea3e6ad9081c902859bbb80f9f840377cb4\"
/usr/bin/ld: /tmp/cc9mWJPn.o: in function `Connection::Connect(char const*, char const*)':
executor.cc:(.text._ZN10Connection7ConnectEPKcS1_[_ZN10Connection7ConnectEPKcS1_]+0x104): 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



Tested on:

commit:         bc04acf4 Add linux-next specific files for 20251204
git tree:       linux-next
kernel config:  https://syzkaller.appspot.com/x/.config?x=a94030c847137a18
dashboard link: https://syzkaller.appspot.com/bug?extid=d222f4b7129379c3d5bc
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1731d01a580000