CVE: CVE-2023-53671
Published: 2025-10-07
Description: In the Linux kernel, the following vulnerability has been resolved:

srcu: Delegate work to the boot cpu if using SRCU_SIZE_SMALL

Commit 994f706872e6 ("srcu: Make Tree SRCU able to operate without
snp_node array") assumes that cpu 0 is always online.  However, there
really are situations when some other CPU is the boot CPU, for example,
when booting a kdump kernel with the maxcpus=1 boot parameter.

On PowerPC, the kdump kernel can hang as follows:
...
[    1.740036] systemd[1]: Hostname set to <xyz.com>
[  243.686240] INFO: task systemd:1 blocked for more than 122 seconds.
[  243.686264]       Not tainted 6.1.0-rc1 #1
[  243.686272] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  243.686281] task:systemd         state:D stack:0     pid:1     ppid:0      flags:0x00042000
[  243.686296] Call Trace:
[  243.686301] [c[PII_REDACTED]57640] [c[PII_REDACTED]57670] 0xc[PII_REDACTED]57670 (unreliable)
[  243.686317] [c[PII_REDACTED]57830] [c[PII_REDACTED]1dec0] __switch_to+0x130/0x220
[  243.686333] [c[PII_REDACTED]57890] [c000000010f607b8] __schedule+0x1f8/0x580
[  243.686347] [c[PII_REDACTED]57940] [c000000010f60bb4] schedule+0x74/0x140
[  243.686361] [c[PII_REDACTED]579b0] [c000000010f699b8] schedule_timeout+0x168/0x1c0
[  243.686374] [c[PII_REDACTED]57a80] [c000000010f61de8] __wait_for_common+0x148/0x360
[  243.686387] [c[PII_REDACTED]57b20] [c[PII_REDACTED]76bb0] __flush_work.isra.0+0x1c0/0x3d0
[  243.686401] [c[PII_REDACTED]57bb0] [c[PII_REDACTED]f2768] fsnotify_wait_marks_destroyed+0x28/0x40
[  243.686415] [c[PII_REDACTED]57bd0] [c[PII_REDACTED]f21b8] fsnotify_destroy_group+0x68/0x160
[  243.686428] [c[PII_REDACTED]57c40] [c[PII_REDACTED]f6500] inotify_release+0x30/0xa0
[  243.686440] [c[PII_REDACTED]57cb0] [c[PII_REDACTED]751a8] __fput+0xc8/0x350
[  243.686452] [c[PII_REDACTED]57d00] [c[PII_REDACTED]7d524] task_work_run+0xe4/0x170
[  243.686464] [c[PII_REDACTED]57d50] [c[PII_REDACTED]20e94] do_notify_resume+0x134/0x140
[  243.686478] [c[PII_REDACTED]57d80] [c[PII_REDACTED]2eb18] interrupt_exit_user_prepare_main+0x198/0x270
[  243.686493] [c[PII_REDACTED]57de0] [c[PII_REDACTED]2ec60] syscall_exit_prepare+0x70/0x180
[  243.686505] [c[PII_REDACTED]57e10] [c[PII_REDACTED]0bf7c] system_call_vectored_common+0xfc/0x280
[  243.686520] --- interrupt: 3000 at 0x7fffa47d5ba4
[  243.686528] NIP:  00007fffa47d5ba4 LR: [PII_REDACTED] CTR: [PII_REDACTED]
[  243.686538] REGS: c[PII_REDACTED]57e80 TRAP: 3000   Not tainted  (6.1.0-rc1)
[  243.686548] MSR: [PII_REDACTED]00d033 <SF,EE,PR,ME,IR,DR,RI,LE>  CR: 42044440  XER: 00000000
[  243.686572] IRQMASK: 0
[  243.686572] GPR00: [PII_REDACTED] 00007ffffa[PII_REDACTED]7fffa48e7200 [PII_REDACTED]
[  243.686572] GPR04: [PII_REDACTED][PII_REDACTED]00000a [PII_REDACTED] [PII_REDACTED]
[  243.686572] GPR08: 000001000c172dd0 [PII_REDACTED] [PII_REDACTED] [PII_REDACTED]
[  243.686572] GPR12: [PII_REDACTED] 00007fffa4ff4bc0 [PII_REDACTED] [PII_REDACTED]
[  243.686572] GPR16: [PII_REDACTED] [PII_REDACTED] [PII_REDACTED] [PII_REDACTED]
[  243.686572] GPR20:[PII_REDACTED]dfdc50[PII_REDACTED]00000e [PII_REDACTED] [PII_REDACTED]
[  243.686572] GPR24: 00007ffffa606ae0 [PII_REDACTED] 000001000c[PII_REDACTED]01000c172570
[  243.686572] GPR28: 000001000c[PII_REDACTED]01000c[PII_REDACTED]01000c172e00 00007fffa4fedd98
[  243.686683] NIP [00007fffa47d5ba4] 0x7fffa47d5ba4
[  243.686691] LR [[PII_REDACTED]] 0x0
[  243.686698] --- interrupt: 3000
[  243.686708] INFO: task kworker/u16:1:24 blocked for more than 122 seconds.
[  243.686717]       Not tainted 6.1.0-rc1 #1
[  243.686724] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  243.686733] task:kworker/u16:1   state:D stack:0     pid:24    ppid:2      flags:0x00000800
[  243.686747] Workqueue: events_unbound fsnotify_mark_destroy_workfn
[  243.686758] Call Trace:
[  243.686762] [c[PII_REDACTED]736e0] [c00000004fd91000] 0xc00000004fd91000 (unreliable)
[  243.686775] [c[PII_REDACTED]738d0] [c[PII_REDACTED]1dec0] __switch_to+0x130/0x220
[  243.686788] [c[PII_REDACTED]73930] [c000000010f607b8] __schedule+0x1f8/0x
---truncated---
CVSS Score: 5.5 (MEDIUM)
References: https://git.kernel.org/stable/c/2c4d26dad76eadaa45a24543e311e9ce5d09f04e; https://git.kernel.org/stable/c/7f24626d6dd844bfc6d1f492d214d29c86d02550; https://git.kernel.org/stable/c/c7c0bc03fa44942fe0fdc5ac52cda6e11529c0ea