[moderation] [kernel?] KCSAN: data-race in prepare_kernel_cred / prepare_kernel_cred

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e9565e23cd89 Merge tag 'sched_ext-for-6.15-rc6-fixes' of g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=117b0f68580000
kernel config: https://syzkaller.appspot.com/x/.config?x=340628a183bd72b7
dashboard link: https://syzkaller.appspot.com/bug?extid=cd4a8fc88284fecb5e52
compiler: Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
CC: [linux-...@vger.kernel.org linux-secu...@vger.kernel.org pa...@paul-moore.com ser...@kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7760d80d328a/disk-e9565e23.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2c71089606c3/vmlinux-e9565e23.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a6195fa2645a/bzImage-e9565e23.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cd4a8f...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in prepare_kernel_cred / prepare_kernel_cred

write to 0xffffffff8685f8f0 of 4 bytes by task 783 on cpu 0:
get_cred_rcu include/linux/cred.h:228 [inline]
get_task_cred kernel/cred.c:162 [inline]
prepare_kernel_cred+0xf5/0x680 kernel/cred.c:593
_request_firmware+0x446/0xbb0 drivers/base/firmware_loader/main.c:909
request_firmware drivers/base/firmware_loader/main.c:992 [inline]
cache_firmware drivers/base/firmware_loader/main.c:1330 [inline]
__async_dev_cache_fw_image+0x66/0x160 drivers/base/firmware_loader/main.c:1444
async_run_entry_fn+0x52/0x180 kernel/async.c:129
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3319
worker_thread+0x582/0x770 kernel/workqueue.c:3400
kthread+0x489/0x510 kernel/kthread.c:464
ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:153
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffffffff8685f848 of 184 bytes by task 3333 on cpu 1:
prepare_kernel_cred+0x114/0x680 kernel/cred.c:595
_request_firmware+0x446/0xbb0 drivers/base/firmware_loader/main.c:909
request_firmware drivers/base/firmware_loader/main.c:992 [inline]
cache_firmware drivers/base/firmware_loader/main.c:1330 [inline]
__async_dev_cache_fw_image+0x66/0x160 drivers/base/firmware_loader/main.c:1444
async_run_entry_fn+0x52/0x180 kernel/async.c:129
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3319
worker_thread+0x582/0x770 kernel/workqueue.c:3400
kthread+0x489/0x510 kernel/kthread.c:464
ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:153
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3333 Comm: kworker/u8:6 Not tainted 6.15.0-rc6-syzkaller-00047-ge9565e23cd89 #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Workqueue: async async_run_entry_fn
==================================================================
netdevsim netdevsim0 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 20001 - 0
netdevsim netdevsim0 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 20001 - 0
netdevsim netdevsim0 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 20001 - 0
netdevsim netdevsim0 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 20001 - 0
bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
bond0 (unregistering): (slave macvlan1): Releasing backup interface
veth1_vlan: left allmulticast mode
bond0 (unregistering): Released all slaves
bond1 (unregistering): Released all slaves
bond2 (unregistering): Released all slaves
bond3 (unregistering): Released all slaves
bond4 (unregistering): Released all slaves
bond5 (unregistering): Released all slaves
batman_adv: batadv0: Removing interface: batadv_slave_0
batman_adv: batadv0: Removing interface: batadv_slave_1
team_slave_1 (unregistering): left promiscuous mode
team0 (unregistering): Port device team_slave_1 removed
team_slave_0 (unregistering): left promiscuous mode
team0 (unregistering): Port device team_slave_0 removed
dummy0 (unregistering): left promiscuous mode
team0 (unregistering): Port device dummy0 removed
IPVS: stop unused estimator thread 0...
netdevsim netdevsim6 netdevsim3 (unregistering): unset [0, 0] type 1 family 0 port 8472 - 0
netdevsim netdevsim6 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim6 netdevsim2 (unregistering): unset [0, 0] type 1 family 0 port 8472 - 0
netdevsim netdevsim6 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim6 netdevsim1 (unregistering): unset [0, 0] type 1 family 0 port 8472 - 0
netdevsim netdevsim6 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim6 netdevsim0 (unregistering): unset [0, 0] type 1 family 0 port 8472 - 0
netdevsim netdevsim6 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim7 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim7 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim7 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim7 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim8 netdevsim3 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim8 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim8 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim8 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
team0: Port device netdevsim0 removed
bond0: left allmulticast mode
bond_slave_0: left allmulticast mode
bond_slave_1: left allmulticast mode
bond0: left promiscuous mode
bond_slave_0: left promiscuous mode
bond_slave_1: left promiscuous mode
bridge0: port 3(bond0) entered disabled state
bridge_slave_1: left allmulticast mode
bridge_slave_1: left promiscuous mode
bridge0: port 2(bridge_slave_1) entered disabled state
bridge_slave_0: left allmulticast mode
bridge_slave_0: left promiscuous mode
bridge0: port 1(bridge_slave_0) entered disabled state
team0: left allmulticast mode
team_slave_0: left allmulticast mode
team_slave_1: left allmulticast mode
bridge0: port 3(team0) entered disabled state
bridge_slave_1: left allmulticast mode
bridge_slave_1: left promiscuous mode
bridge0: port 2(bridge_slave_1) entered disabled state
bridge_slave_0: left allmulticast mode
bridge_slave_0: left promiscuous mode
bridge0: port 1(bridge_slave_0) entered disabled state
bridge_slave_1: left allmulticast mode
bridge_slave_1: left promiscuous mode
bridge0: port 2(bridge_slave_1) entered disabled state
bridge_slave_0: left allmulticast mode
bridge_slave_0: left promiscuous mode
bridge0: port 1(bridge_slave_0) entered disabled state
bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
bond0 (unregistering): Released all slaves
bond1 (unregistering): Released all slaves
bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
bond0 (unregistering): Released all slaves
bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
bond0 (unregistering): Released all slaves
(unregistering): Released all slaves
bond1 (unregistering): Released all slaves
bond2 (unregistering): Released all slaves
bond3 (unregistering): Released all slaves
bond4 (unregistering): Released all slaves
bond5 (unregistering): Released all slaves
bond0 (unregistering): Released all slaves
tipc: Left network mode
tipc: Left network mode
hsr_slave_0: left promiscuous mode
hsr_slave_1: left promiscuous mode
batman_adv: batadv0: Interface deactivated: batadv_slave_0
batman_adv: batadv0: Removing interface: batadv_slave_0
batman_adv: batadv0: Interface deactivated: batadv_slave_1
batman_adv: batadv0: Removing interface: batadv_slave_1
hsr_slave_0: left promiscuous mode
hsr_slave_1: left promiscuous mode
batman_adv: batadv0: Interface deactivated: batadv_slave_0
batman_adv: batadv0: Removing interface: batadv_slave_0
batman_adv: batadv0: Interface deactivated: batadv_slave_1
batman_adv: batadv0: Removing interface: batadv_slave_1
hsr_slave_0: left promiscuous mode
hsr_slave_1: left promiscuous mode
batman_adv: batadv0: Interface deactivated: batadv_slave_0
batman_adv: batadv0: Removing interface: batadv_slave_0
batman_adv: batadv0: Interface deactivated: batadv_slave_1
batman_adv: batadv0: Removing interface: batadv_slave_1
hsr_slave_0: left promiscuous mode
hsr_slave_1: left promiscuous mode
veth1_macvtap: left promiscuous mode
veth0_macvtap: left promiscuous mode
veth1_macvtap: left promiscuous mode
veth0_macvtap: left promiscuous mode
veth1_vlan: left promiscuous mode
veth0_vlan: left promiscuous mode
veth1_macvtap: left promiscuous mode
veth0_macvtap: left promiscuous mode
veth1_vlan: left promiscuous mode
veth0_vlan: left promiscuous mode
pimreg (unregistering): left allmulticast mode
team0 (unregistering): Port device team_slave_1 removed
team0 (unregistering): Port device team_slave_0 removed
team_slave_1 (unregistering): left promiscuous mode
team0 (unregistering): Port device team_slave_1 removed
team_slave_0 (unregistering): left promiscuous mode
team0 (unregistering): Port device team_slave_0 removed
team0 (unregistering): Port device team_slave_1 removed
team0 (unregistering): Port device team_slave_0 removed
IPVS: stop unused estimator thread 0...


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.