Re: [syzbot] [bpf?] KMSAN: uninit-value in htab_lru_percpu_map_lookup_percpu_elem

[syzbot <syzbot+1971e47e5210c718db3c@syzkaller.appspotmail.com>]

Hello,

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

61ee5452e1b2df'
[   49.565928][    T1] ima: Allocated hash algorithm: sha256
[   49.572049][    T1] ima: No architecture policies found
[   49.578974][    T1] evm: Initialising EVM extended attributes:
[   49.585220][    T1] evm: security.selinux (disabled)
[   49.590764][    T1] evm: security.SMACK64 (disabled)
[   49.595968][    T1] evm: security.SMACK64EXEC (disabled)
[   49.601835][    T1] evm: security.SMACK64TRANSMUTE (disabled)
[   49.608506][    T1] evm: security.SMACK64MMAP (disabled)
[   49.614038][    T1] evm: security.apparmor
[   49.618451][    T1] evm: security.ima
[   49.622436][    T1] evm: security.capability
[   49.627502][    T1] evm: HMAC attrs: 0x1
[   49.636597][    T1] PM:   Magic number: 12:387:485
[   49.642665][    T1] usb usb18-port6: hash matches
[   49.648999][    T1] usb usb17-port7: hash matches
[   49.655774][    T1] printk: legacy console [netcon0] enabled
[   49.662095][    T1] netconsole: network logging started
[   49.669345][    T1] gtp: GTP module loaded (pdp ctx size 128 bytes)
[   49.678657][    T1] rdma_rxe: loaded
[   49.684488][    T1] cfg80211: Loading compiled-in X.509 certificates for regulatory database
[   49.706425][    T1] Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
[   49.724152][    T1] Loaded X.509 cert 'wens: 61c038651aabdcf94bd0ac7ff06c7248db18c600'
[   49.733298][    T1] clk: Disabling unused clocks
[   49.739237][    T1] ALSA device list:
[   49.743250][    T1]   #0: Dummy 1
[   49.747040][    T1]   #1: Loopback 1
[   49.750957][    T1]   #2: Virtual MIDI Card 1
[   49.761414][   T43] platform regulatory.0: Direct firmware load for regulatory.db failed with error -2
[   49.771525][   T43] platform regulatory.0: Falling back to sysfs fallback for: regulatory.db
[   49.781327][    T1] md: Waiting for all devices to be available before autodetect
[   49.789841][    T1] md: If you don't use raid, use raid=noautodetect
[   49.796709][    T1] md: Autodetecting RAID arrays.
[   49.801753][    T1] md: autorun ...
[   49.805475][    T1] md: ... autorun DONE.
[   49.898217][    T1] EXT4-fs (sda1): mounted filesystem 5941fea2-f5fa-4b4e-b5ef-9af118b27b95 ro with ordered data mode. Quota mode: none.
[   49.911801][    T1] VFS: Mounted root (ext4 filesystem) readonly on device 8:1.
[   49.935132][    T1] devtmpfs: mounted
[   50.190758][    T1] Freeing unused kernel image (initmem) memory: 37036K
[   50.202710][    T1] Write protecting the kernel read-only data: 262144k
[   50.249033][    T1] Freeing unused kernel image (rodata/data gap) memory: 1808K
[   51.885170][    T1] x86/mm: Checked W+X mappings: passed, no W+X pages found.
[   51.895531][    T1] x86/mm: Checking user space page tables
[   53.391911][    T1] x86/mm: Checked W+X mappings: passed, no W+X pages found.
[   53.401141][    T1] Failed to set sysctl parameter 'kernel.hung_task_all_cpu_backtrace=1': parameter not found
[   53.422983][    T1] Failed to set sysctl parameter 'max_rcu_stall_to_panic=1': parameter not found
[   53.434940][    T1] Run /sbin/init as init process
[   54.937583][ T4446] mount (4446) used greatest stack depth: 8144 bytes left
[   55.037752][ T4447] EXT4-fs (sda1): re-mounted 5941fea2-f5fa-4b4e-b5ef-9af118b27b95 r/w. Quota mode: none.
mount: mounting smackfs on /sys/fs/smackfs failed: No such file or directory
mount: mounting selinuxfs on /sys/fs/selinux failed: No such file or directory
[   55.371085][ T4450] mount (4450) used greatest stack depth: 5568 bytes left
Starting syslogd: OK
Starting acpid: OK
Starting klogd: OK
Running sysctl: OK
Populating /dev using udev: [   59.193733][ T4480] udevd[4480]: starting version 3.2.11
[   62.697884][ T4481] udevd[4481]: starting eudev-3.2.11
[   62.710663][ T4480] udevd (4480) used greatest stack depth: 5264 bytes left
done
Starting system message bus: done
Starting iptables: OK
Starting network: OK
Starting dhcpcd...
dhcpcd-9.4.1 starting
dev: loaded udev
DUID 00:04:98:24:4c:28:99:7c:d9:70:fe:51:ca:fe:56:33:2c:7d
forked to background, child pid 4693
no interfaces have a carrier
[  110.077072][ T4694] 8021q: adding VLAN 0 to HW filter on device bond0
[  110.114606][ T4694] eql: remember to turn off Van-Jacobson compression on your slave devices
Starting sshd: [  111.638151][   T43] cfg80211: failed to load regulatory.db
OK


syzkaller

syzkaller login: [  115.668614][    C0] =====================================================
[  115.675770][    C0] BUG: KMSAN: uninit-value in receive_buf+0x25e3/0x5fd0
[  115.682913][    C0]  receive_buf+0x25e3/0x5fd0
[  115.687725][    C0]  virtnet_poll+0xd1c/0x23c0
[  115.692508][    C0]  __napi_poll+0xe7/0x980
[  115.697035][    C0]  net_rx_action+0x82a/0x1850
[  115.701947][    C0]  handle_softirqs+0x1ce/0x800
[  115.706920][    C0]  __irq_exit_rcu+0x68/0x120
[  115.711977][    C0]  irq_exit_rcu+0x12/0x20
[  115.716495][    C0]  common_interrupt+0x94/0xa0
[  115.721393][    C0]  asm_common_interrupt+0x2b/0x40
[  115.726789][    C0]  kmsan_metadata_is_contiguous+0x11/0x1e0
[  115.732777][    C0]  kmsan_get_shadow_origin_ptr+0x2a/0xb0
[  115.738611][    C0]  __msan_metadata_ptr_for_load_8+0x24/0x40
[  115.744707][    C0]  kmem_cache_alloc_noprof+0x1b0/0xb20
[  115.750434][    C0]  anon_vma_fork+0x2c8/0xad0
[  115.755224][    C0]  copy_mm+0x1b57/0x3ca0
[  115.759770][    C0]  copy_process+0x26f7/0x5b90
[  115.764746][    C0]  kernel_clone+0x401/0x1040
[  115.769622][    C0]  __x64_sys_clone+0x25c/0x360
[  115.774688][    C0]  x64_sys_call+0x2a45/0x3b90
[  115.779774][    C0]  do_syscall_64+0xcd/0x1e0
[  115.784469][    C0]  entry_SYSCALL_64_after_hwframe+0x77/0x7f
[  115.790699][    C0] 
[  115.793105][    C0] Uninit was created at:
[  115.797720][    C0]  __alloc_pages_noprof+0x9d6/0xe70
[  115.803195][    C0]  alloc_pages_mpol_noprof+0x299/0x990
[  115.808997][    C0]  alloc_pages_noprof+0x1bf/0x1e0
[  115.814258][    C0]  skb_page_frag_refill+0x2bf/0x7c0
[  115.819691][    C0]  virtnet_rq_alloc+0x43/0xbb0
[  115.824701][    C0]  try_fill_recv+0x3f0/0x2f50
[  115.829565][    C0]  virtnet_open+0x1cc/0xb00
[  115.834627][    C0]  __dev_open+0x546/0x6f0
[  115.839151][    C0]  __dev_change_flags+0x309/0x9a0
[  115.844358][    C0]  dev_change_flags+0x8e/0x1d0
[  115.849310][    C0]  devinet_ioctl+0x13ec/0x22c0
[  115.854298][    C0]  inet_ioctl+0x4bd/0x6d0
[  115.858825][    C0]  sock_do_ioctl+0xb7/0x540
[  115.863572][    C0]  sock_ioctl+0x727/0xd70
[  115.868115][    C0]  __se_sys_ioctl+0x261/0x450
[  115.872978][    C0]  __x64_sys_ioctl+0x96/0xe0
[  115.877780][    C0]  x64_sys_call+0x18c0/0x3b90
[  115.882898][    C0]  do_syscall_64+0xcd/0x1e0
[  115.887598][    C0]  entry_SYSCALL_64_after_hwframe+0x77/0x7f
[  115.894138][    C0] 
[  115.896697][    C0] CPU: 0 PID: 4833 Comm: dhcpcd-run-hook Not tainted 6.10.0-rc3-syzkaller-00022-g78161c936167 #0
[  115.907699][    C0] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
[  115.918263][    C0] =====================================================
[  115.925284][    C0] Disabling lock debugging due to kernel taint
[  115.931598][    C0] Kernel panic - not syncing: kmsan.panic set ...
[  115.938121][    C0] CPU: 0 PID: 4833 Comm: dhcpcd-run-hook Tainted: G    B              6.10.0-rc3-syzkaller-00022-g78161c936167 #0
[  115.951147][    C0] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
[  115.961392][    C0] Call Trace:
[  115.964735][    C0]  <IRQ>
[  115.967631][    C0]  dump_stack_lvl+0x216/0x2d0
[  115.972463][    C0]  ? kmsan_get_shadow_origin_ptr+0x4d/0xb0
[  115.978480][    C0]  dump_stack+0x1e/0x30
[  115.982741][    C0]  panic+0x4e2/0xcd0
[  115.986784][    C0]  ? kmsan_get_metadata+0x81/0x1d0
[  115.992099][    C0]  kmsan_report+0x2d5/0x2e0
[  115.996714][    C0]  ? kmsan_get_metadata+0x146/0x1d0
[  116.002010][    C0]  ? __msan_warning+0x95/0x120
[  116.007035][    C0]  ? receive_buf+0x25e3/0x5fd0
[  116.011916][    C0]  ? virtnet_poll+0xd1c/0x23c0
[  116.016876][    C0]  ? __napi_poll+0xe7/0x980
[  116.021526][    C0]  ? net_rx_action+0x82a/0x1850
[  116.026608][    C0]  ? handle_softirqs+0x1ce/0x800
[  116.031670][    C0]  ? __irq_exit_rcu+0x68/0x120
[  116.036542][    C0]  ? irq_exit_rcu+0x12/0x20
[  116.041163][    C0]  ? common_interrupt+0x94/0xa0
[  116.046211][    C0]  ? asm_common_interrupt+0x2b/0x40
[  116.051608][    C0]  ? kmsan_metadata_is_contiguous+0x11/0x1e0
[  116.057724][    C0]  ? kmsan_get_shadow_origin_ptr+0x2a/0xb0
[  116.063734][    C0]  ? __msan_metadata_ptr_for_load_8+0x24/0x40
[  116.069923][    C0]  ? kmem_cache_alloc_noprof+0x1b0/0xb20
[  116.075660][    C0]  ? anon_vma_fork+0x2c8/0xad0
[  116.080547][    C0]  ? copy_mm+0x1b57/0x3ca0
[  116.085158][    C0]  ? copy_process+0x26f7/0x5b90
[  116.090122][    C0]  ? kernel_clone+0x401/0x1040
[  116.095009][    C0]  ? __x64_sys_clone+0x25c/0x360
[  116.100114][    C0]  ? x64_sys_call+0x2a45/0x3b90
[  116.105088][    C0]  ? do_syscall_64+0xcd/0x1e0
[  116.109969][    C0]  ? entry_SYSCALL_64_after_hwframe+0x77/0x7f
[  116.116530][    C0]  ? kmsan_internal_memmove_metadata+0x17b/0x230
[  116.123065][    C0]  ? kmsan_get_metadata+0x146/0x1d0
[  116.128453][    C0]  ? kmsan_get_metadata+0x146/0x1d0
[  116.133856][    C0]  ? page_to_skb+0xdae/0x1620
[  116.138636][    C0]  ? kmsan_get_metadata+0x146/0x1d0
[  116.143993][    C0]  __msan_warning+0x95/0x120
[  116.148713][    C0]  receive_buf+0x25e3/0x5fd0
[  116.153414][    C0]  ? kmsan_get_metadata+0x146/0x1d0
[  116.158922][    C0]  ? kmsan_get_shadow_origin_ptr+0x4d/0xb0
[  116.164985][    C0]  virtnet_poll+0xd1c/0x23c0
[  116.169720][    C0]  ? __pfx_virtnet_poll+0x10/0x10
[  116.174942][    C0]  __napi_poll+0xe7/0x980
[  116.179431][    C0]  ? kmsan_get_metadata+0x146/0x1d0
[  116.184754][    C0]  net_rx_action+0x82a/0x1850
[  116.189579][    C0]  ? sched_clock_cpu+0x55/0x870
[  116.194593][    C0]  ? __pfx_net_rx_action+0x10/0x10
[  116.199846][    C0]  handle_softirqs+0x1ce/0x800
[  116.204734][    C0]  __irq_exit_rcu+0x68/0x120
[  116.209452][    C0]  irq_exit_rcu+0x12/0x20
[  116.213891][    C0]  common_interrupt+0x94/0xa0
[  116.218689][    C0]  </IRQ>
[  116.221668][    C0]  <TASK>
[  116.224666][    C0]  asm_common_interrupt+0x2b/0x40
[  116.229996][    C0] RIP: 0010:kmsan_metadata_is_contiguous+0x11/0x1e0
[  116.236882][    C0] Code: 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66 0f 1f 00 55 48 89 e5 41 57 41 56 41 55 41 54 53 <48> 83 ec 28 41 b7 01 48 85 f6 0f 84 fa 00 00 00 49 89 f6 49 89 fd
[  116.256797][    C0] RSP: 0018:ffff88811798b800 EFLAGS: 00000202
[  116.263179][    C0] RAX: 0000000000000000 RBX: 0000000000000286 RCX: 000000023fd2eed8
[  116.271335][    C0] RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff88813fcaaed0
[  116.279678][    C0] RBP: ffff88811798b828 R08: ffffea000000000f R09: 0000000000000000
[  116.287830][    C0] R10: ffff88811718b8e0 R11: 0000000000000004 R12: 0000000000000000
[  116.296069][    C0] R13: 00000000000aaed0 R14: 0000000000000000 R15: ffff88813fcaaed0
[  116.304176][    C0]  kmsan_get_shadow_origin_ptr+0x2a/0xb0
[  116.309957][    C0]  __msan_metadata_ptr_for_load_8+0x24/0x40
[  116.315975][    C0]  kmem_cache_alloc_noprof+0x1b0/0xb20
[  116.321559][    C0]  ? anon_vma_fork+0x2c8/0xad0
[  116.326458][    C0]  anon_vma_fork+0x2c8/0xad0
[  116.331167][    C0]  ? kmsan_get_shadow_origin_ptr+0x4d/0xb0
[  116.337093][    C0]  ? kmsan_get_metadata+0x146/0x1d0
[  116.342519][    C0]  copy_mm+0x1b57/0x3ca0
[  116.346908][    C0]  copy_process+0x26f7/0x5b90
[  116.351896][    C0]  kernel_clone+0x401/0x1040
[  116.356596][    C0]  ? kmsan_get_metadata+0x146/0x1d0
[  116.361896][    C0]  ? kmsan_get_metadata+0x146/0x1d0
[  116.367640][    C0]  ? __msan_memset+0xf5/0x1b0
[  116.372457][    C0]  __x64_sys_clone+0x25c/0x360
[  116.377377][    C0]  x64_sys_call+0x2a45/0x3b90
[  116.382201][    C0]  do_syscall_64+0xcd/0x1e0
[  116.386840][    C0]  ? clear_bhb_loop+0x25/0x80
[  116.391663][    C0]  entry_SYSCALL_64_after_hwframe+0x77/0x7f
[  116.397791][    C0] RIP: 0033:0x7f5286b82a12
[  116.402300][    C0] Code: 41 5d 41 5e 41 5f c3 64 48 8b 04 25 10 00 00 00 45 31 c0 31 d2 31 f6 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 76 10 48 8b 15 e7 43 0f 00 f7 d8 64 89 02 48 83
[  116.422246][    C0] RSP: 002b:00007ffc58a2d428 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
[  116.430864][    C0] RAX: ffffffffffffffda RBX: 000055b776464901 RCX: 00007f5286b82a12
[  116.438942][    C0] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
[  116.447162][    C0] RBP: 000055b776465ba0 R08: 0000000000000000 R09: 3c00000000001001
[  116.455213][    C0] R10: 00007f5286a48650 R11: 0000000000000246 R12: 000055b776468368
[  116.463463][    C0] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[  116.471794][    C0]  </TASK>
[  116.475163][    C0] Kernel Offset: disabled
[  116.479655][    C0] 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=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.21.4'
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 -ffile-prefix-map=/tmp/go-build572936856=/tmp/go-build -gno-record-gcc-switches'

git status (err=<nil>)
HEAD detached at c8349e4853
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}}' ./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
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=c8349e48534ea6d8f01515335d95de8ebf5da8df -X 'github.com/google/syzkaller/prog.gitRevisionDate=20240412-102842'" "-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=c8349e48534ea6d8f01515335d95de8ebf5da8df -X 'github.com/google/syzkaller/prog.gitRevisionDate=20240412-102842'" "-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=c8349e48534ea6d8f01515335d95de8ebf5da8df -X 'github.com/google/syzkaller/prog.gitRevisionDate=20240412-102842'" "-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=\"c8349e48534ea6d8f01515335d95de8ebf5da8df\"


Error text is too large and was truncated, full error text is at:
https://syzkaller.appspot.com/x/error.txt?x=11313a2e980000


Tested on:

commit:         78161c93 kernel/bpf: KMSAN: uninit-value in htab_lru_p..
git tree:       https://linux.googlesource.com/linux/kernel/git/torvalds/linux
kernel config:  https://syzkaller.appspot.com/x/.config?x=3486f1660f47f855
dashboard link: https://syzkaller.appspot.com/bug?extid=1971e47e5210c718db3c
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.