Message-ID: <696a4733.050a0220.58bed.0051.GAE@google.com>
Date: Fri, 16 Jan 2026 06:12:03 -0800
From: syzbot <syzbot+7ff4013eabad1407b70a@...kaller.appspotmail.com>
To: dmantipov@...dex.ru, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [net?] [virt?] memory leak in napi_skb_cache_get (2)

Hello,

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

SYZFAIL: failed to recv rpc

SYZFAIL: failed to recv rpc
fd=3 want=4 recv=0 n=0 (errno 9: Bad file descriptor)


Warning: Permanently added '10.128.0.10' (ED25519) to the list of known hosts.
2026/01/16 14:10:52 parsed 1 programs
[   44.294122][ T5814] cgroup: Unknown subsys name 'net'
[   44.398859][ T5814] cgroup: Unknown subsys name 'cpuset'
[   44.405854][ T5814] cgroup: Unknown subsys name 'rlimit'
Setting up swapspace version 1, size = 127995904 bytes
[   53.013278][ T5814] Adding 124996k swap on ./swap-file.  Priority:0 extents:1 across:124996k 
[   54.500294][ T5823] soft_limit_in_bytes is deprecated and will be removed. Please report your usecase to linux-mm@...ck.org if you depend on this functionality.
[   54.608994][ T5828] chnl_net:caif_netlink_parms(): no params data found
[   54.628582][ T5828] bridge0: port 1(bridge_slave_0) entered blocking state
[   54.636082][ T5828] bridge0: port 1(bridge_slave_0) entered disabled state
[   54.643353][ T5828] bridge_slave_0: entered allmulticast mode
[   54.649598][ T5828] bridge_slave_0: entered promiscuous mode
[   54.656058][ T5828] bridge0: port 2(bridge_slave_1) entered blocking state
[   54.663386][ T5828] bridge0: port 2(bridge_slave_1) entered disabled state
[   54.670684][ T5828] bridge_slave_1: entered allmulticast mode
[   54.676839][ T5828] bridge_slave_1: entered promiscuous mode
[   54.689143][ T5828] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
[   54.699215][ T5828] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link
[   54.712955][ T5828] team0: Port device team_slave_0 added
[   54.719167][ T5828] team0: Port device team_slave_1 added
[   54.729336][ T5828] batman_adv: batadv0: Adding interface: batadv_slave_0
[   54.736293][ T5828] 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.
[   54.763030][ T5828] batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active
[   54.774111][ T5828] batman_adv: batadv0: Adding interface: batadv_slave_1
[   54.781299][ T5828] 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.
[   54.807205][ T5828] batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
[   54.824808][ T5828] hsr_slave_0: entered promiscuous mode
[   54.830630][ T5828] hsr_slave_1: entered promiscuous mode
[   54.860130][ T5828] netdevsim netdevsim0 netdevsim0: renamed from eth0
[   54.867897][ T5828] netdevsim netdevsim0 netdevsim1: renamed from eth1
[   54.875407][ T5828] netdevsim netdevsim0 netdevsim2: renamed from eth2
[   54.883438][ T5828] netdevsim netdevsim0 netdevsim3: renamed from eth3
[   54.895706][ T5828] bridge0: port 2(bridge_slave_1) entered blocking state
[   54.903087][ T5828] bridge0: port 2(bridge_slave_1) entered forwarding state
[   54.910540][ T5828] bridge0: port 1(bridge_slave_0) entered blocking state
[   54.917805][ T5828] bridge0: port 1(bridge_slave_0) entered forwarding state
[   54.935223][ T5828] 8021q: adding VLAN 0 to HW filter on device bond0
[   54.944496][ T1097] bridge0: port 1(bridge_slave_0) entered disabled state
[   54.952080][ T1097] bridge0: port 2(bridge_slave_1) entered disabled state
[   54.961923][ T5828] 8021q: adding VLAN 0 to HW filter on device team0
[   54.970290][   T31] bridge0: port 1(bridge_slave_0) entered blocking state
[   54.978091][   T31] bridge0: port 1(bridge_slave_0) entered forwarding state
[   54.987218][ T1097] bridge0: port 2(bridge_slave_1) entered blocking state
[   54.994500][ T1097] bridge0: port 2(bridge_slave_1) entered forwarding state
[   55.039547][ T5828] 8021q: adding VLAN 0 to HW filter on device batadv0
[   55.054546][ T5828] veth0_vlan: entered promiscuous mode
[   55.061919][ T5828] veth1_vlan: entered promiscuous mode
[   55.076976][ T5828] veth0_macvtap: entered promiscuous mode
[   55.084154][ T5828] veth1_macvtap: entered promiscuous mode
[   55.093396][ T5828] batman_adv: batadv0: Interface activated: batadv_slave_0
[   55.102918][ T5828] batman_adv: batadv0: Interface activated: batadv_slave_1
[   55.112557][   T35] netdevsim netdevsim0 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
[   55.121687][   T35] netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
[   55.131221][   T35] netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
[   55.140240][   T35] netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
[   55.174860][ T5135] Bluetooth: hci0: unexpected cc 0x0c03 length: 249 > 1
[   55.182317][ T5135] Bluetooth: hci0: unexpected cc 0x1003 length: 249 > 9
[   55.190115][ T5135] Bluetooth: hci0: unexpected cc 0x1001 length: 249 > 9
[   55.197820][ T5135] Bluetooth: hci0: unexpected cc 0x0c23 length: 249 > 4
[   55.205612][ T5135] Bluetooth: hci0: unexpected cc 0x0c38 length: 249 > 2
[   55.213126][   T35] netdevsim netdevsim0 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   55.264430][   T35] netdevsim netdevsim0 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   55.280201][   T35] netdevsim netdevsim0 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   55.330018][   T35] netdevsim netdevsim0 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   55.689878][ T1097] wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[   55.699624][ T1097] wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50
[   55.710618][   T31] wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[   55.718824][   T31] wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
2026/01/16 14:11:06 executed programs: 0
[   58.091653][   T35] bridge_slave_1: left allmulticast mode
[   58.102588][   T35] bridge_slave_1: left promiscuous mode
[   58.108508][   T35] bridge0: port 2(bridge_slave_1) entered disabled state
[   58.116091][   T35] bridge_slave_0: left allmulticast mode
[   58.122201][   T35] bridge_slave_0: left promiscuous mode
[   58.127843][   T35] bridge0: port 1(bridge_slave_0) entered disabled state
[   58.180190][   T35] bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
[   58.189656][   T35] bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
[   58.198993][   T35] bond0 (unregistering): Released all slaves
[   58.259317][   T35] hsr_slave_0: left promiscuous mode
[   58.265523][   T35] hsr_slave_1: left promiscuous mode
[   58.271603][   T35] batman_adv: batadv0: Interface deactivated: batadv_slave_0
[   58.279163][   T35] batman_adv: batadv0: Removing interface: batadv_slave_0
[   58.286699][   T35] batman_adv: batadv0: Interface deactivated: batadv_slave_1
[   58.295364][   T35] batman_adv: batadv0: Removing interface: batadv_slave_1
[   58.305538][   T35] veth1_macvtap: left promiscuous mode
[   58.311288][   T35] veth0_macvtap: left promiscuous mode
[   58.316792][   T35] veth1_vlan: left promiscuous mode
[   58.322304][   T35] veth0_vlan: left promiscuous mode
[   58.348816][   T35] team0 (unregistering): Port device team_slave_1 removed
[   58.357049][   T35] team0 (unregistering): Port device team_slave_0 removed
[   61.970096][   T50] Bluetooth: hci0: unexpected cc 0x0c03 length: 249 > 1
[   61.977258][   T50] Bluetooth: hci0: unexpected cc 0x1003 length: 249 > 9
[   61.984564][   T50] Bluetooth: hci0: unexpected cc 0x1001 length: 249 > 9
[   61.992772][   T50] Bluetooth: hci0: unexpected cc 0x0c23 length: 249 > 4
[   62.000321][   T50] Bluetooth: hci0: unexpected cc 0x0c38 length: 249 > 2
[   62.037930][ T5992] chnl_net:caif_netlink_parms(): no params data found
[   62.060242][ T5992] bridge0: port 1(bridge_slave_0) entered blocking state
[   62.067305][ T5992] bridge0: port 1(bridge_slave_0) entered disabled state
[   62.074552][ T5992] bridge_slave_0: entered allmulticast mode
[   62.081059][ T5992] bridge_slave_0: entered promiscuous mode
[   62.087481][ T5992] bridge0: port 2(bridge_slave_1) entered blocking state
[   62.094777][ T5992] bridge0: port 2(bridge_slave_1) entered disabled state
[   62.102020][ T5992] bridge_slave_1: entered allmulticast mode
[   62.108293][ T5992] bridge_slave_1: entered promiscuous mode
[   62.119097][ T5992] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
[   62.128803][ T5992] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link
[   62.142261][ T5992] team0: Port device team_slave_0 added
[   62.148546][ T5992] team0: Port device team_slave_1 added
[   62.158789][ T5992] batman_adv: batadv0: Adding interface: batadv_slave_0
[   62.165743][ T5992] 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.
[   62.192242][ T5992] batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active
[   62.203221][ T5992] batman_adv: batadv0: Adding interface: batadv_slave_1
[   62.210357][ T5992] 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.
[   62.236450][ T5992] batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
[   62.253773][ T5992] hsr_slave_0: entered promiscuous mode
[   62.259633][ T5992] hsr_slave_1: entered promiscuous mode
[   62.393088][ T5992] netdevsim netdevsim0 netdevsim0: renamed from eth0
[   62.401279][ T5992] netdevsim netdevsim0 netdevsim1: renamed from eth1
[   62.409186][ T5992] netdevsim netdevsim0 netdevsim2: renamed from eth2
[   62.417131][ T5992] netdevsim netdevsim0 netdevsim3: renamed from eth3
[   62.443459][ T5992] bridge0: port 2(bridge_slave_1) entered blocking state
[   62.450583][ T5992] bridge0: port 2(bridge_slave_1) entered forwarding state
[   62.457991][ T5992] bridge0: port 1(bridge_slave_0) entered blocking state
[   62.465076][ T5992] bridge0: port 1(bridge_slave_0) entered forwarding state
[   62.490336][ T5992] 8021q: adding VLAN 0 to HW filter on device bond0
[   62.501084][ T5992] 8021q: adding VLAN 0 to HW filter on device team0
[   62.510795][   T35] bridge0: port 1(bridge_slave_0) entered disabled state
[   62.525081][   T35] bridge0: port 2(bridge_slave_1) entered disabled state
[   62.536338][   T35] bridge0: port 1(bridge_slave_0) entered blocking state
[   62.543466][   T35] bridge0: port 1(bridge_slave_0) entered forwarding state
[   62.553663][ T1097] bridge0: port 2(bridge_slave_1) entered blocking state
[   62.560872][ T1097] bridge0: port 2(bridge_slave_1) entered forwarding state
[   62.620990][ T5992] 8021q: adding VLAN 0 to HW filter on device batadv0
[   62.639673][ T5992] veth0_vlan: entered promiscuous mode
[   62.648812][ T5992] veth1_vlan: entered promiscuous mode
[   62.662593][ T5992] veth0_macvtap: entered promiscuous mode
[   62.670638][ T5992] veth1_macvtap: entered promiscuous mode
[   62.681839][ T5992] batman_adv: batadv0: Interface activated: batadv_slave_0
[   62.692261][ T5992] batman_adv: batadv0: Interface activated: batadv_slave_1
[   62.701961][   T31] netdevsim netdevsim0 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
[   62.727953][   T31] netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
[   62.736951][   T31] netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
[   62.749749][   T35] wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[   62.763144][   T35] wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50
SYZFAIL: failed to recv rpc
fd=3 want=4 recv=0 n=0 (errno 9: Bad file descriptor)
[   62.770995][   T31] netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
[   62.783728][   T58] wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[   62.797558][   T58] wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50


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-build2226822454=/tmp/go-build -gno-record-gcc-switches'
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMOD='/syzkaller/jobs/linux/gopath/src/github.com/google/syzkaller/go.mod'
GOMODCACHE='/syzkaller/jobs/linux/gopath/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/syzkaller/jobs/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 d6526ea3e6
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/ccR9rODE.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:         983d014a kernel: modules: Add SPDX license identifier ..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel config:  https://syzkaller.appspot.com/x/.config?x=87bc41cae23d2144
dashboard link: https://syzkaller.appspot.com/bug?extid=7ff4013eabad1407b70a
compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=13b0139a580000

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