Re: [syzbot] [kernel?] general protection fault in put_ipc_ns

[syzbot <syzbot+b4c65e7d749285a82467@syzkaller.appspotmail.com>]

Hello,

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

adv_slave_0
[   82.746048][ T5860] 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.
[   82.773161][ T5860] batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active
[   82.785953][ T5860] batman_adv: batadv0: Adding interface: batadv_slave_1
[   82.794164][ T5860] 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.
[   82.820942][ T5860] batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
[   82.862768][ T5860] hsr_slave_0: entered promiscuous mode
[   82.869651][ T5860] hsr_slave_1: entered promiscuous mode
[   83.005933][ T5860] netdevsim netdevsim0 netdevsim0: renamed from eth0
[   83.019731][ T5860] netdevsim netdevsim0 netdevsim1: renamed from eth1
[   83.030171][ T5860] netdevsim netdevsim0 netdevsim2: renamed from eth2
[   83.040986][ T5860] netdevsim netdevsim0 netdevsim3: renamed from eth3
[   83.071236][ T5860] bridge0: port 2(bridge_slave_1) entered blocking state
[   83.078685][ T5860] bridge0: port 2(bridge_slave_1) entered forwarding state
[   83.086669][ T5860] bridge0: port 1(bridge_slave_0) entered blocking state
[   83.093877][ T5860] bridge0: port 1(bridge_slave_0) entered forwarding state
[   83.151826][ T5860] 8021q: adding VLAN 0 to HW filter on device bond0
[   83.171295][   T13] bridge0: port 1(bridge_slave_0) entered disabled state
[   83.180117][   T13] bridge0: port 2(bridge_slave_1) entered disabled state
[   83.196524][ T5860] 8021q: adding VLAN 0 to HW filter on device team0
[   83.211219][ T3472] bridge0: port 1(bridge_slave_0) entered blocking state
[   83.218434][ T3472] bridge0: port 1(bridge_slave_0) entered forwarding state
[   83.234149][ T3472] bridge0: port 2(bridge_slave_1) entered blocking state
[   83.241297][ T3472] bridge0: port 2(bridge_slave_1) entered forwarding state
[   83.404613][ T5860] 8021q: adding VLAN 0 to HW filter on device batadv0
[   83.449917][ T5860] veth0_vlan: entered promiscuous mode
[   83.462775][ T5860] veth1_vlan: entered promiscuous mode
[   83.492993][ T5860] veth0_macvtap: entered promiscuous mode
[   83.503348][ T5860] veth1_macvtap: entered promiscuous mode
[   83.523457][ T5860] batman_adv: batadv0: Interface activated: batadv_slave_0
[   83.537529][ T5860] batman_adv: batadv0: Interface activated: batadv_slave_1
[   83.554721][   T13] netdevsim netdevsim0 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
[   83.566197][   T13] netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
[   83.575668][   T13] netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
[   83.586196][   T13] netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
[   83.724406][   T13] netdevsim netdevsim0 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   83.805326][   T13] netdevsim netdevsim0 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   83.870907][   T13] netdevsim netdevsim0 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   83.935311][ T5149] Bluetooth: hci0: unexpected cc 0x0c03 length: 249 > 1
[   83.945133][ T5149] Bluetooth: hci0: unexpected cc 0x1003 length: 249 > 9
[   83.954176][ T5149] Bluetooth: hci0: unexpected cc 0x1001 length: 249 > 9
[   83.962161][ T5149] ==================================================================
[   83.970240][ T5149] BUG: KASAN: slab-use-after-free in hci_cmd_work+0x5d0/0x7b0
[   83.977772][ T5149] Read of size 2 at addr ffff88807912b178 by task kworker/u9:1/5149
[   83.985826][ T5149] 
[   83.988159][ T5149] CPU: 1 UID: 0 PID: 5149 Comm: kworker/u9:1 Not tainted syzkaller #0 PREEMPT(full) 
[   83.988173][ T5149] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
[   83.988181][ T5149] Workqueue: hci0 hci_cmd_work
[   83.988200][ T5149] Call Trace:
[   83.988208][ T5149]  <TASK>
[   83.988212][ T5149]  dump_stack_lvl+0x189/0x250
[   83.988226][ T5149]  ? __virt_addr_valid+0x1c8/0x5c0
[   83.988242][ T5149]  ? rcu_is_watching+0x15/0xb0
[   83.988261][ T5149]  ? __pfx_dump_stack_lvl+0x10/0x10
[   83.988277][ T5149]  ? rcu_is_watching+0x15/0xb0
[   83.988294][ T5149]  ? lock_release+0x4b/0x3d0
[   83.988309][ T5149]  ? _raw_spin_lock_irqsave+0xb3/0xf0
[   83.988328][ T5149]  ? __virt_addr_valid+0x1c8/0x5c0
[   83.988348][ T5149]  ? __virt_addr_valid+0x4a5/0x5c0
[   83.988368][ T5149]  print_report+0xca/0x240
[   83.988388][ T5149]  ? hci_cmd_work+0x5d0/0x7b0
[   83.988402][ T5149]  kasan_report+0x118/0x150
[   83.988420][ T5149]  ? hci_cmd_work+0x5d0/0x7b0
[   83.988439][ T5149]  hci_cmd_work+0x5d0/0x7b0
[   83.988454][ T5149]  ? process_one_work+0x868/0x15e0
[   83.988471][ T5149]  process_one_work+0x93a/0x15e0
[   83.988487][ T5149]  ? __lock_acquire+0xab9/0xd20
[   83.988510][ T5149]  ? __pfx_process_one_work+0x10/0x10
[   83.988528][ T5149]  ? assign_work+0x3a1/0x410
[   83.988544][ T5149]  worker_thread+0x9b0/0xee0
[   83.988569][ T5149]  kthread+0x711/0x8a0
[   83.988589][ T5149]  ? __pfx_worker_thread+0x10/0x10
[   83.988605][ T5149]  ? __pfx_kthread+0x10/0x10
[   83.988625][ T5149]  ? _raw_spin_unlock_irq+0x23/0x50
[   83.988642][ T5149]  ? lockdep_hardirqs_on+0x9c/0x150
[   83.988663][ T5149]  ? __pfx_kthread+0x10/0x10
[   83.988682][ T5149]  ret_from_fork+0x599/0xb30
[   83.988699][ T5149]  ? __pfx_ret_from_fork+0x10/0x10
[   83.988717][ T5149]  ? __switch_to_asm+0x39/0x70
[   83.988735][ T5149]  ? __switch_to_asm+0x33/0x70
[   83.988753][ T5149]  ? __pfx_kthread+0x10/0x10
[   83.988770][ T5149]  ret_from_fork_asm+0x1a/0x30
[   83.988794][ T5149]  </TASK>
[   83.988800][ T5149] 
[   84.178661][ T5149] Allocated by task 51:
[   84.182802][ T5149]  kasan_save_track+0x3e/0x80
[   84.187470][ T5149]  __kasan_slab_alloc+0x6c/0x80
[   84.192305][ T5149]  kmem_cache_alloc_node_noprof+0x43c/0x710
[   84.198202][ T5149]  __alloc_skb+0x112/0x2d0
[   84.202607][ T5149]  hci_cmd_sync_alloc+0x3d/0x3b0
[   84.207729][ T5149]  __hci_cmd_sync_sk+0x1a7/0xc70
[   84.212679][ T5149]  hci_dev_open_sync+0x1756/0x2dc0
[   84.217791][ T5149]  hci_power_on+0x1b4/0x720
[   84.222285][ T5149]  process_one_work+0x93a/0x15e0
[   84.227216][ T5149]  worker_thread+0x9b0/0xee0
[   84.231822][ T5149]  kthread+0x711/0x8a0
[   84.235883][ T5149]  ret_from_fork+0x599/0xb30
[   84.240457][ T5149]  ret_from_fork_asm+0x1a/0x30
[   84.245211][ T5149] 
[   84.247532][ T5149] Freed by task 5891:
[   84.251512][ T5149]  kasan_save_track+0x3e/0x80
[   84.256186][ T5149]  kasan_save_free_info+0x46/0x50
[   84.261299][ T5149]  __kasan_slab_free+0x5c/0x80
[   84.266105][ T5149]  kmem_cache_free+0x197/0x640
[   84.270862][ T5149]  vhci_read+0x49a/0x5b0
[   84.275105][ T5149]  vfs_read+0x200/0xa30
[   84.279274][ T5149]  ksys_read+0x145/0x250
[   84.283498][ T5149]  do_syscall_64+0xfa/0xfa0
[   84.287991][ T5149]  entry_SYSCALL_64_after_hwframe+0x77/0x7f
[   84.293891][ T5149] 
[   84.296210][ T5149] The buggy address belongs to the object at ffff88807912b140
[   84.296210][ T5149]  which belongs to the cache skbuff_head_cache of size 240
[   84.310805][ T5149] The buggy address is located 56 bytes inside of
[   84.310805][ T5149]  freed 240-byte region [ffff88807912b140, ffff88807912b230)
[   84.324512][ T5149] 
[   84.326836][ T5149] The buggy address belongs to the physical page:
[   84.333246][ T5149] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7912b
[   84.341996][ T5149] flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
[   84.349273][ T5149] page_type: f5(slab)
[   84.353249][ T5149] raw: 00fff00000000000 ffff8881416a7000 dead000000000122 0000000000000000
[   84.361818][ T5149] raw: 0000000000000000 00000000800c000c 00000000f5000000 0000000000000000
[   84.370380][ T5149] page dumped because: kasan: bad access detected
[   84.376783][ T5149] page_owner tracks the page as allocated
[   84.382566][ T5149] page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5149, tgid 5149 (kworker/u9:1), ts 83954148103, free_ts 83898959204
[   84.401827][ T5149]  post_alloc_hook+0x240/0x2a0
[   84.406596][ T5149]  get_page_from_freelist+0x2365/0x2440
[   84.412140][ T5149]  __alloc_frozen_pages_noprof+0x181/0x370
[   84.417940][ T5149]  alloc_pages_mpol+0x232/0x4a0
[   84.422780][ T5149]  allocate_slab+0x86/0x3b0
[   84.427274][ T5149]  ___slab_alloc+0xf56/0x1990
[   84.431938][ T5149]  __slab_alloc+0x65/0x100
[   84.436343][ T5149]  kmem_cache_alloc_noprof+0x40f/0x700
[   84.441793][ T5149]  skb_clone+0x212/0x3a0
[   84.446024][ T5149]  hci_event_packet+0x3f4/0x1260
[   84.450947][ T5149]  hci_rx_work+0x45d/0xfc0
[   84.455353][ T5149]  process_one_work+0x93a/0x15e0
[   84.460293][ T5149]  worker_thread+0x9b0/0xee0
[   84.464934][ T5149]  kthread+0x711/0x8a0
[   84.468988][ T5149]  ret_from_fork+0x599/0xb30
[   84.473570][ T5149]  ret_from_fork_asm+0x1a/0x30
[   84.478320][ T5149] page last free pid 23 tgid 23 stack trace:
[   84.484280][ T5149]  __free_frozen_pages+0xbc8/0xd30
[   84.489382][ T5149]  rcu_core+0xcab/0x1770
[   84.493645][ T5149]  handle_softirqs+0x27d/0x880
[   84.498484][ T5149]  run_ksoftirqd+0x9b/0x100
[   84.502973][ T5149]  smpboot_thread_fn+0x542/0xa60
[   84.507903][ T5149]  kthread+0x711/0x8a0
[   84.511955][ T5149]  ret_from_fork+0x599/0xb30
[   84.516613][ T5149]  ret_from_fork_asm+0x1a/0x30
[   84.521371][ T5149] 
[   84.523692][ T5149] Memory state around the buggy address:
[   84.529318][ T5149]  ffff88807912b000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[   84.537367][ T5149]  ffff88807912b080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc
[   84.545411][ T5149] >ffff88807912b100: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
[   84.553463][ T5149]                                                                 ^
[   84.561420][ T5149]  ffff88807912b180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[   84.569522][ T5149]  ffff88807912b200: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc
[   84.577564][ T5149] ==================================================================
[   84.589891][ T5149] Kernel panic - not syncing: KASAN: panic_on_warn set ...
[   84.597220][ T5149] CPU: 1 UID: 0 PID: 5149 Comm: kworker/u9:1 Not tainted syzkaller #0 PREEMPT(full) 
[   84.606680][ T5149] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
[   84.616748][ T5149] Workqueue: hci0 hci_cmd_work
[   84.621514][ T5149] Call Trace:
[   84.624787][ T5149]  <TASK>
[   84.627716][ T5149]  dump_stack_lvl+0x99/0x250
[   84.632304][ T5149]  ? __asan_memcpy+0x40/0x70
[   84.636901][ T5149]  ? __pfx_dump_stack_lvl+0x10/0x10
[   84.642098][ T5149]  ? __pfx__printk+0x10/0x10
[   84.646681][ T5149]  vpanic+0x237/0x6d0
[   84.650648][ T5149]  ? __pfx_vpanic+0x10/0x10
[   84.655134][ T5149]  ? preempt_schedule+0xae/0xc0
[   84.659973][ T5149]  ? __pfx_preempt_schedule+0x10/0x10
[   84.665424][ T5149]  panic+0xb9/0xc0
[   84.669144][ T5149]  ? __pfx_panic+0x10/0x10
[   84.673547][ T5149]  ? _raw_spin_unlock_irqrestore+0xfd/0x110
[   84.679427][ T5149]  ? is_module_address+0x17/0xf0
[   84.684353][ T5149]  ? hci_cmd_work+0x5d0/0x7b0
[   84.689108][ T5149]  check_panic_on_warn+0x89/0xb0
[   84.694039][ T5149]  ? hci_cmd_work+0x5d0/0x7b0
[   84.698796][ T5149]  end_report+0x6f/0x160
[   84.703026][ T5149]  kasan_report+0x129/0x150
[   84.707528][ T5149]  ? hci_cmd_work+0x5d0/0x7b0
[   84.712310][ T5149]  hci_cmd_work+0x5d0/0x7b0
[   84.716803][ T5149]  ? process_one_work+0x868/0x15e0
[   84.721908][ T5149]  process_one_work+0x93a/0x15e0
[   84.726862][ T5149]  ? __lock_acquire+0xab9/0xd20
[   84.731730][ T5149]  ? __pfx_process_one_work+0x10/0x10
[   84.737108][ T5149]  ? assign_work+0x3a1/0x410
[   84.741711][ T5149]  worker_thread+0x9b0/0xee0
[   84.746302][ T5149]  kthread+0x711/0x8a0
[   84.750365][ T5149]  ? __pfx_worker_thread+0x10/0x10
[   84.755468][ T5149]  ? __pfx_kthread+0x10/0x10
[   84.760051][ T5149]  ? _raw_spin_unlock_irq+0x23/0x50
[   84.765238][ T5149]  ? lockdep_hardirqs_on+0x9c/0x150
[   84.770437][ T5149]  ? __pfx_kthread+0x10/0x10
[   84.775024][ T5149]  ret_from_fork+0x599/0xb30
[   84.779604][ T5149]  ? __pfx_ret_from_fork+0x10/0x10
[   84.784708][ T5149]  ? __switch_to_asm+0x39/0x70
[   84.789477][ T5149]  ? __switch_to_asm+0x33/0x70
[   84.794236][ T5149]  ? __pfx_kthread+0x10/0x10
[   84.798902][ T5149]  ret_from_fork_asm+0x1a/0x30
[   84.803663][ T5149]  </TASK>
[   84.807193][ T5149] Kernel Offset: disabled
[   84.811510][ T5149] Rebooting in 86400 seconds..


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-build3725946350=/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 07e030dea
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=07e030dea6e6d9ca88b75bb3be2810f47083b328 -X github.com/google/syzkaller/prog.gitRevisionDate=20251112-115923"  ./sys/syz-sysgen | grep -q false || go install -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=07e030dea6e6d9ca88b75bb3be2810f47083b328 -X github.com/google/syzkaller/prog.gitRevisionDate=20251112-115923"  ./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=07e030dea6e6d9ca88b75bb3be2810f47083b328 -X github.com/google/syzkaller/prog.gitRevisionDate=20251112-115923"  -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=\"07e030dea6e6d9ca88b75bb3be2810f47083b328\"
/usr/bin/ld: /tmp/cciUCEVm.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


Error text is too large and was truncated, full error text is at:
https://syzkaller.appspot.com/x/error.txt?x=15e3fb42580000


Tested on:

commit:         187dac29 Add linux-next specific files for 20251118
git tree:       linux-next
kernel config:  https://syzkaller.appspot.com/x/.config?x=f3aa05e175a53177
dashboard link: https://syzkaller.appspot.com/bug?extid=b4c65e7d749285a82467
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=10513212580000