CVE-2025-21943 Information

Description

In the Linux kernel the following vulnerability has been resolved:

gpio: aggregator: protect driver attr handlers against module unload

Both new_device_store and delete_device_store touch module global resources (e.g. gpio_aggregator_lock). To prevent race conditions with module unload a reference needs to be held.

Add try_module_get() in these handlers.

For new_device_store this eliminates what appears to be the most dangerous scenario: if an id is allocated from gpio_aggregator_idr but platform_device_register has not yet been called or completed a concurrent module unload could fail to unregister/delete the device leaving behind a dangling platform device/GPIO forwarder. This can result in various issues. The following simple reproducer demonstrates these problems:

!/bin/bash while :; do note: whether ‘gpiochip0 0’ exists or not does not matter. echo ‘gpiochip0 0’ > /sys/bus/platform/drivers/gpio-aggregator/new_device done & while :; do modprobe gpio-aggregator modprobe -r gpio-aggregator done & wait

Starting with the following warning several kinds of warnings will appear and the system may become unstable:

————[ cut here ]———— list_del corruption ffff888103e2e980->next is LIST_POISON1 (dead000000000100) WARNING: CPU: 1 PID: 1327 at lib/list_debug.c:56 __list_del_entry_valid_or_report+0xa3/0x120 […] RIP: 0010:__list_del_entry_valid_or_report+0xa3/0x120 […] Call Trace: ? __list_del_entry_valid_or_report+0xa3/0x120 ? __warn.cold+0x93/0xf2 ? __list_del_entry_valid_or_report+0xa3/0x120 ? report_bug+0xe6/0x170 ? __irq_work_queue_local+0x39/0xe0 ? handle_bug+0x58/0x90 ? exc_invalid_op+0x13/0x60 ? asm_exc_invalid_op+0x16/0x20 ? __list_del_entry_valid_or_report+0xa3/0x120 gpiod_remove_lookup_table+0x22/0x60 new_device_store+0x315/0x350 [gpio_aggregator] kernfs_fop_write_iter+0x137/0x1f0 vfs_write+0x262/0x430 ksys_write+0x60/0xd0 do_syscall_64+0x6c/0x180 entry_SYSCALL_64_after_hwframe+0x76/0x7e […] —[ end trace 0000000000000000 ]—

Reference

https://git.kernel.org/stable/c/12f65d1203507f7db3ba59930fe29a3b8eee9945 https://git.kernel.org/stable/c/56281a76b805b5ac61feb5d580139695a22f87f0 https://git.kernel.org/stable/c/807789018186cf508ceb3a1f8f02935cd195717b https://git.kernel.org/stable/c/8fb07fb1bba91d45846ed8605c3097fe67a7d54c https://git.kernel.org/stable/c/9334c88fc2fbc6836b307d269fcc1744c69701c0 https://git.kernel.org/stable/c/d99dc8f7ea01ee1b21306e0eda8eb18a4af80db6 https://git.kernel.org/stable/c/fd6aa1f8cbe0979eb66ac32ebc231bf0b10a2117