Description
In the Linux kernel, the following vulnerability has been resolved: gpiolib: cdev: Fix use after free in lineinfo_changed_notify The use-after-free issue occurs as follows: when the GPIO chip device file is being closed by invoking gpio_chrdev_release(), watched_lines is freed by bitmap_free(), but the unregistration of lineinfo_changed_nb notifier chain failed due to waiting write rwsem. Additionally, one of the GPIO chip's lines is also in the release process and holds the notifier chain's read rwsem. Consequently, a race condition leads to the use-after-free of watched_lines. Here is the typical stack when issue happened: [free] gpio_chrdev_release() --> bitmap_free(cdev->watched_lines) <-- freed --> blocking_notifier_chain_unregister() --> down_write(&nh->rwsem) <-- waiting rwsem --> __down_write_common() --> rwsem_down_write_slowpath() --> schedule_preempt_disabled() --> schedule() [use] st54spi_gpio_dev_release() --> gpio_free() --> gpiod_free() --> gpiod_free_commit() --> gpiod_line_state_notify() --> blocking_notifier_call_chain() --> down_read(&nh->rwsem); <-- held rwsem --> notifier_call_chain() --> lineinfo_changed_notify() --> test_bit(xxxx, cdev->watched_lines) <-- use after free The side effect of the use-after-free issue is that a GPIO line event is being generated for userspace where it shouldn't. However, since the chrdev is being closed, userspace won't have the chance to read that event anyway. To fix the issue, call the bitmap_free() function after the unregistration of lineinfo_changed_nb notifier chain.
Product status
51c1064e82e77b39a49889287ca50709303e2f26 (git) before 2dfbb920a89bdc58087672ad5325dc6c588b6860
51c1064e82e77b39a49889287ca50709303e2f26 (git) before 2d008d4961b039d2edce8976289773961b7e5fb5
51c1064e82e77b39a49889287ca50709303e2f26 (git) before d38c49f7bdf14381270736299e2ff68ec248a017
51c1064e82e77b39a49889287ca50709303e2f26 (git) before 95ca7c90eaf5ea8a8460536535101e3e81160e2a
51c1064e82e77b39a49889287ca50709303e2f26 (git) before ca710b5f40b8b16fdcad50bebd47f50e4c62d239
51c1064e82e77b39a49889287ca50709303e2f26 (git) before 02f6b0e1ec7e0e7d059dddc893645816552039da
5.7
Any version before 5.7
5.10.234 (semver)
5.15.177 (semver)
6.1.127 (semver)
6.6.31 (semver)
6.8.10 (semver)
6.9 (original_commit_for_fix)
References
git.kernel.org/...c/2dfbb920a89bdc58087672ad5325dc6c588b6860
git.kernel.org/...c/2d008d4961b039d2edce8976289773961b7e5fb5
git.kernel.org/...c/d38c49f7bdf14381270736299e2ff68ec248a017
git.kernel.org/...c/95ca7c90eaf5ea8a8460536535101e3e81160e2a
git.kernel.org/...c/ca710b5f40b8b16fdcad50bebd47f50e4c62d239
git.kernel.org/...c/02f6b0e1ec7e0e7d059dddc893645816552039da
