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* Re: [syzbot] [media?] KASAN: slab-use-after-free Read in __dynamic_dev_dbg
       [not found] <20260918051712.24978-1-kartikey406@gmail.com>
@ 2026-09-18  5:31 ` syzbot
  0 siblings, 0 replies; 2+ messages in thread
From: syzbot @ 2026-09-18  5:31 UTC (permalink / raw)
  To: kartikey406, linux-kernel, syzkaller-bugs

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)
execution of simple program fails: NOTFAIL: arptable checkpoint: getsockopt(ARPT_SO_GET_ENTRIES) failed. table=filter (errno 22: Invalid argument).


Warning: Permanently added '[localhost]:54685' (ED25519) to the list of known hosts.
2026/09/18 05:30:02 parsed 1 programs
2026/09/18 05:30:02 serving rpc on tcp://32951
[   47.745155][ T5743] cgroup: Unknown subsys name 'net'
[   47.852384][ T5743] cgroup: Unknown subsys name 'cpuset'
[   47.856459][ T5743] cgroup: Unknown subsys name 'rlimit'
Setting up swapspace version 1, size = 127995904 bytes
[   48.886846][ T5743] Adding 124996k swap on ./swap-file.  Priority:0 extents:1 across:124996k 
[   51.358683][ T5755] soft_limit_in_bytes is deprecated and will be removed. Writing any value to this file has no effect. Please report your usecase to linux-mm@kvack.org if you depend on this functionality.
[   51.365586][ T5755] ebtables: xtables 32bit compat interface no longer supported in namespaces and will be removed soon.
[   51.375529][ T5755] arp_tables: xtables 32bit compat interface no longer supported in namespaces and will be removed soon.
[   51.379024][   T37] wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[   51.379041][   T37] wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50
[   51.518286][  T228] wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
[   51.518311][  T228] wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
[   52.518770][   T66] Bluetooth: hci0: unexpected cc 0x0c03 length: 249 > 1
[   52.526974][   T66] Bluetooth: hci0: unexpected cc 0x1003 length: 249 > 9
[   52.535189][   T66] Bluetooth: hci0: unexpected cc 0x1001 length: 249 > 9
[   52.539813][   T66] Bluetooth: hci0: unexpected cc 0x0c23 length: 249 > 4
[   52.540335][   T66] Bluetooth: hci0: unexpected cc 0x0c38 length: 249 > 2
[   52.541643][ T5769] bridge0: port 1(bridge_slave_0) entered blocking state
[   52.542691][ T5769] bridge0: port 1(bridge_slave_0) entered disabled state
[   52.542775][ T5769] bridge_slave_0: entered allmulticast mode
[   52.545963][ T5769] bridge_slave_0: entered promiscuous mode
[   52.558325][ T5769] bridge0: port 2(bridge_slave_1) entered blocking state
[   52.558372][ T5769] bridge0: port 2(bridge_slave_1) entered disabled state
[   52.558428][ T5769] bridge_slave_1: entered allmulticast mode
[   52.560598][ T5769] bridge_slave_1: entered promiscuous mode
[   52.584378][ T5769] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
[   52.611029][ T5769] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link
[   52.648950][ T5769] team0: Port device team_slave_0 added
[   52.660980][ T5769] team0: Port device team_slave_1 added
[   52.719483][ T5769] batman_adv: batadv0: Adding interface: batadv_slave_0
[   52.719500][ T5769] 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.
[   52.719521][ T5769] batman_adv: batadv0: Not using interface batadv_slave_0 (retrying later): interface not active
[   52.737518][ T5769] batman_adv: batadv0: Adding interface: batadv_slave_1
[   52.737533][ T5769] 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.
[   52.737551][ T5769] batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
[   52.909782][ T5809] ip_tables: xtables 32bit compat interface no longer supported in namespaces and will be removed soon.
[   52.910132][ T5809] ip6_tables: xtables 32bit compat interface no longer supported in namespaces and will be removed soon.
[   52.936259][ T5769] hsr_slave_0: entered promiscuous mode
[   52.942371][ T5769] hsr_slave_1: entered promiscuous mode
[   53.428872][ T5769] netdevsim netdevsim4 netdevsim0: renamed from eth0
[   53.436610][ T5769] 8021q: adding VLAN 0 to HW filter on device netdevsim0
[   53.437232][ T5769] netdevsim netdevsim4 netdevsim1: renamed from eth1
[   53.441662][ T5769] 8021q: adding VLAN 0 to HW filter on device netdevsim1
[   53.442889][ T5769] netdevsim netdevsim4 netdevsim2: renamed from eth2
[   53.457545][ T5769] 8021q: adding VLAN 0 to HW filter on device netdevsim2
[   53.468017][ T5769] netdevsim netdevsim4 netdevsim3: renamed from eth3
[   53.472353][ T5769] 8021q: adding VLAN 0 to HW filter on device netdevsim3
[   53.554786][ T5769] 8021q: adding VLAN 0 to HW filter on device bond0
[   53.574890][ T5769] 8021q: adding VLAN 0 to HW filter on device team0
[   53.583923][   T37] bridge0: port 1(bridge_slave_0) entered blocking state
[   53.584039][   T37] bridge0: port 1(bridge_slave_0) entered forwarding state
[   53.592421][   T37] bridge0: port 2(bridge_slave_1) entered blocking state
[   53.592552][   T37] bridge0: port 2(bridge_slave_1) entered forwarding state
[   53.917390][ T5769] 8021q: adding VLAN 0 to HW filter on device batadv0
[   54.072213][ T5769] veth0_vlan: entered promiscuous mode
[   54.077626][ T5769] veth1_vlan: entered promiscuous mode
[   54.092533][ T5769] veth0_macvtap: entered promiscuous mode
[   54.094902][ T5769] veth1_macvtap: entered promiscuous mode
[   54.106231][ T5769] batman_adv: batadv0: Interface activated: batadv_slave_0
[   54.111897][ T5769] batman_adv: batadv0: Interface activated: batadv_slave_1
[   54.141095][   T12] netdevsim netdevsim4 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
[   54.141137][   T12] netdevsim netdevsim4 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
[   54.141165][   T12] netdevsim netdevsim4 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
[   54.141194][   T12] netdevsim netdevsim4 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
[   54.184771][   T12] netdevsim netdevsim4 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
SYZFAIL: failed to recv rpc
fd=3 want=4 recv=0 n=0 (errno 9: Bad file descriptor)
execution of simple program fails: NOTFAIL: arptable checkpoint: getsockopt(ARPT_SO_GET_ENTRIES) failed. table=filter (errno 22: Invalid argument).
[   54.261521][   T12] netdevsim netdevsim4 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   54.340989][   T12] netdevsim netdevsim4 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   54.428677][   T12] netdevsim netdevsim4 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
[   55.676684][   T12] bridge_slave_1: left allmulticast mode
[   55.676720][   T12] bridge_slave_1: left promiscuous mode
[   55.679098][   T12] bridge0: port 2(bridge_slave_1) entered disabled state
[   55.685646][   T12] bridge_slave_0: left allmulticast mode
[   55.685669][   T12] bridge_slave_0: left promiscuous mode
[   55.685832][   T12] bridge0: port 1(bridge_slave_0) entered disabled state
[   55.793840][   T12] bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
[   55.796673][   T12] bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
[   55.798080][   T12] bond0 (unregistering): Released all slaves
[   55.875181][ T5450] 8021q: adding VLAN 0 to HW filter on device eth2
[   55.907074][   T12] hsr_slave_0: left promiscuous mode
[   55.907494][   T12] hsr_slave_1: left promiscuous mode
[   55.907913][   T12] batman_adv: batadv0: Interface deactivated: batadv_slave_0
[   55.907928][   T12] batman_adv: batadv0: Removing interface: batadv_slave_0
[   55.908530][   T12] batman_adv: batadv0: Interface deactivated: batadv_slave_1
[   55.908540][   T12] batman_adv: batadv0: Removing interface: batadv_slave_1
[   55.917255][   T12] veth1_macvtap: left promiscuous mode
[   55.917296][   T12] veth0_macvtap: left promiscuous mode
[   55.917345][   T12] veth1_vlan: left promiscuous mode
[   55.917401][   T12] veth0_vlan: left promiscuous mode
[   56.037674][   T12] team0 (unregistering): Port device team_slave_1 removed
[   56.054457][   T12] team0 (unregistering): Port device team_slave_0 removed
[   56.103005][ T5450] 8021q: adding VLAN 0 to HW filter on device eth3
[   56.289426][ T5450] 8021q: adding VLAN 0 to HW filter on device eth4
[   56.450317][ T5450] 8021q: adding VLAN 0 to HW filter on device eth5


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-build3502523694=/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='go1.26.0'
GOWORK=''
PKG_CONFIG='pkg-config'

git status (err=<nil>)
HEAD detached at f41e228a2e7
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=f41e228a2e7b883d75a56aa602070c9893ccb54c -X github.com/google/syzkaller/prog.gitRevisionDate=20260915-092900"  ./sys/syz-sysgen | grep -q false || go install -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=f41e228a2e7b883d75a56aa602070c9893ccb54c -X github.com/google/syzkaller/prog.gitRevisionDate=20260915-092900"  ./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=f41e228a2e7b883d75a56aa602070c9893ccb54c -X github.com/google/syzkaller/prog.gitRevisionDate=20260915-092900"  -o ./bin/linux_amd64/syz-execprog github.com/google/syzkaller/tools/syz-execprog
mkdir -p ./bin/linux_386
x86_64-linux-gnu-g++ -o ./bin/linux_386/syz-executor executor/executor.cc \
	-m32 -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_386=1 \
	-DHOSTGOOS_linux=1 -DGIT_REVISION=\"f41e228a2e7b883d75a56aa602070c9893ccb54c\"
/usr/bin/ld: /tmp/ccyeqg4J.o: in function `Connection::Connect(char const*, char const*)':
executor.cc:(.text._ZN10Connection7ConnectEPKcS1_[_ZN10Connection7ConnectEPKcS1_]+0x145): 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
[INFO] Unsupported architecture '386', skipping check.



Tested on:

commit:         5dd1818b Merge tag 'for-next-keys-v7.3-rc4' of git://g..
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=d61c584072d6137
dashboard link: https://syzkaller.appspot.com/bug?extid=9bfac891bdd42eb708fc
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
userspace arch: i386
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1741b8c9580000


^ permalink raw reply	[flat|nested] 2+ messages in thread

* [syzbot] [media?] KASAN: slab-use-after-free Read in __dynamic_dev_dbg
@ 2026-09-16 15:53 syzbot
  0 siblings, 0 replies; 2+ messages in thread
From: syzbot @ 2026-09-16 15:53 UTC (permalink / raw)
  To: linux-kernel, linux-media, mchehab, sean, syzkaller-bugs

Hello,

syzbot found the following issue on:

HEAD commit:    50d05c7c76c9 Merge tag 'landlock-7.3-rc3' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=161003f9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=85bc5cc2fc7394d9
dashboard link: https://syzkaller.appspot.com/bug?extid=9bfac891bdd42eb708fc
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
userspace arch: i386
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1349045e580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10a7e3f9580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-50d05c7c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/303a0ade8f9e/vmlinux-50d05c7c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/70b8ca71442b/bzImage-50d05c7c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9bfac891bdd42eb708fc@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in dev_name include/linux/device.h:934 [inline]
BUG: KASAN: slab-use-after-free in __dynamic_dev_dbg+0x2fc/0x310 lib/dynamic_debug.c:904
Read of size 8 at addr ffff88804cba20c8 by task syz.0.17/6046

CPU: 2 UID: 0 PID: 6046 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x13d/0x4b0 mm/kasan/report.c:482
 kasan_report+0xdf/0x1c0 mm/kasan/report.c:595
 dev_name include/linux/device.h:934 [inline]
 __dynamic_dev_dbg+0x2fc/0x310 lib/dynamic_debug.c:904
 display_close+0x103/0x150 drivers/media/rc/imon.c:580
 __fput+0x3ff/0xb50 fs/file_table.c:512
 task_work_run+0x150/0x240 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x951/0x2ae0 kernel/exit.c:1011
 do_group_exit+0xd5/0x2a0 kernel/exit.c:1154
 get_signal+0x1ec7/0x21e0 kernel/signal.c:3051
 arch_do_signal_or_restart+0x91/0x7a0 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
 exit_to_user_mode_loop+0x139/0x700 kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:336 [inline]
 do_int80_emulation+0x555/0x650 arch/x86/entry/syscall_32.c:169
 asm_int80_emulation+0x1a/0x20 arch/x86/include/asm/idtentry.h:598
RIP: 0023:0xf71575ab
Code: Unable to access opcode bytes at 0xf7157581.
RSP: 002b:00000000ffb6690c EFLAGS: 00000246
 ORIG_RAX: 000000000000010b
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 00000000ffb669a4 RSI: 00000000ffb6699c RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>

Allocated by task 30:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x2f8/0x6d0 mm/slub.c:5563
 _kmalloc_noprof include/linux/slab.h:991 [inline]
 _kzalloc_noprof include/linux/slab.h:1312 [inline]
 usb_set_configuration+0x10cb/0x1c60 drivers/usb/core/message.c:2096
 usb_generic_driver_probe+0xa1/0xe0 drivers/usb/core/generic.c:250
 usb_probe_device+0xef/0x400 drivers/usb/core/driver.c:293
 call_driver_probe drivers/base/dd.c:628 [inline]
 really_probe+0x241/0xa60 drivers/base/dd.c:706
 __driver_probe_device+0x210/0x460 drivers/base/dd.c:868
 driver_probe_device+0x4a/0x140 drivers/base/dd.c:898
 __device_attach_driver+0x1df/0x320 drivers/base/dd.c:1026
 bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:500
 __device_attach+0x1e4/0x4d0 drivers/base/dd.c:1098
 device_initial_probe+0xaf/0xd0 drivers/base/dd.c:1153
 bus_probe_device+0x64/0x160 drivers/base/bus.c:620
 device_add+0x121d/0x1970 drivers/base/core.c:3776
 usb_new_device.part.0+0xcc2/0x1686 drivers/usb/core/hub.c:2708
 usb_new_device include/linux/workqueue.h:715 [inline]
 hub_port_connect drivers/usb/core/hub.c:5580 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5720 [inline]
 port_event drivers/usb/core/hub.c:5884 [inline]
 hub_event.cold+0x1e3/0xe90 drivers/usb/core/hub.c:5966
 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
 process_scheduled_works kernel/workqueue.c:3479 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560
 kthread+0x373/0x450 kernel/kthread.c:436
 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 5842:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2748 [inline]
 slab_free mm/slub.c:6499 [inline]
 kfree+0x22b/0x6d0 mm/slub.c:6792
 device_release+0xd2/0x270 drivers/base/core.c:2640
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1f7/0x640 lib/kobject.c:737
 put_device+0x1f/0x30 drivers/base/core.c:3884
 usb_disable_device+0x44a/0x810 drivers/usb/core/message.c:1485
 usb_disconnect+0x2e2/0x9a0 drivers/usb/core/hub.c:2350
 hub_port_connect drivers/usb/core/hub.c:5420 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5720 [inline]
 port_event drivers/usb/core/hub.c:5884 [inline]
 hub_event+0x1bb1/0x4420 drivers/usb/core/hub.c:5966
 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
 process_scheduled_works kernel/workqueue.c:3479 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560
 kthread+0x373/0x450 kernel/kthread.c:436
 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff88804cba2000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 200 bytes inside of
 freed 2048-byte region [ffff88804cba2000, ffff88804cba2800)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x4cba0
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x4fff00000000040(head|node=1|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 04fff00000000040 ffff88801c042f00 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 04fff00000000040 ffff88801c042f00 dead000000000100 dead000000000122
head: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 04fff00000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5859, tgid 5859 (kworker/1:4), ts 49377453462
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1871
 prep_new_page mm/page_alloc.c:1879 [inline]
 get_page_from_freelist+0x110d/0x35d0 mm/page_alloc.c:3943
 __alloc_frozen_pages_noprof+0x2eb/0x3300 mm/page_alloc.c:5436
 alloc_slab_page mm/slub.c:3347 [inline]
 allocate_slab mm/slub.c:3462 [inline]
 new_slab+0xa9/0x6e0 mm/slub.c:3513
 refill_objects+0xe3/0x410 mm/slub.c:7410
 refill_sheaf mm/slub.c:2885 [inline]
 __pcs_replace_empty_main+0x35e/0x650 mm/slub.c:4774
 alloc_from_pcs mm/slub.c:4850 [inline]
 slab_alloc_node mm/slub.c:4984 [inline]
 __do_kmalloc_node mm/slub.c:5413 [inline]
 __kmalloc_node_track_caller_noprof+0x6a8/0x870 mm/slub.c:5545
 kmalloc_reserve+0xe8/0x350 net/core/skbuff.c:637
 __alloc_skb+0x185/0x710 net/core/skbuff.c:715
 alloc_skb include/linux/skbuff.h:1384 [inline]
 mld_newpack.isra.0+0x18e/0xa20 net/ipv6/mcast.c:1810
 add_grhead+0x299/0x340 net/ipv6/mcast.c:1921
 add_grec+0x1389/0x1930 net/ipv6/mcast.c:2060
 mld_send_cr net/ipv6/mcast.c:2185 [inline]
 mld_ifc_work+0x3c5/0xc10 net/ipv6/mcast.c:2739
 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
 process_scheduled_works kernel/workqueue.c:3479 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560
 kthread+0x373/0x450 kernel/kthread.c:436
page last free pid 5161 tgid 5161 ts 12784202840 stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 __free_pages_prepare mm/page_alloc.c:1418 [inline]
 __free_frozen_pages+0x79f/0x10f0 mm/page_alloc.c:2962
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4683 [inline]
 slab_alloc_node mm/slub.c:4996 [inline]
 kmem_cache_alloc_noprof+0x269/0x6a0 mm/slub.c:5010
 alloc_filename fs/namei.c:147 [inline]
 do_getname+0x35/0x390 fs/namei.c:187
 getname include/linux/fs.h:2557 [inline]
 getname_maybe_null include/linux/fs.h:2564 [inline]
 class_filename_maybe_null_constructor include/linux/fs.h:2588 [inline]
 vfs_fstatat+0xd0/0xe0 fs/stat.c:368
 __do_sys_newfstatat+0x9d/0x120 fs/stat.c:538
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x121/0x770 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88804cba1f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88804cba2000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88804cba2080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff88804cba2100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88804cba2180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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2026-09-18  5:31 ` [syzbot] [media?] KASAN: slab-use-after-free Read in __dynamic_dev_dbg syzbot
2026-09-16 15:53 syzbot

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