Re: [PATCH v7 03/10] ACPI: APEI: GHES: move GHESv2 ack and alloc helpers

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] The EDAC driver initializes and exits by iterating over the `ghes_devs` linked list using `list_for_each_entry_safe()`, but fails to acquire the protective `ghes_devs_mutex`. Concurrent modification of this list by `ghes_probe()` or `ghes_remove()` (e.g., triggered via sysfs bind/unbind) will cause list corruption and use-after-free. This problem wasn't introduced by this patch, but pre-existed in the codebase.
--

--- Patch [3]: [PATCH v7 03/10] ACPI: APEI: GHES: move GHESv2 ack and alloc helpers ---
commit bf19da8163cfc99677668eb5a9ba4a2f8cc72b57
Author: Ahmed Tiba <ahmed.tiba@arm.com>

ACPI: APEI: GHES: move GHESv2 ack and alloc helpers

This commit moves the GHESv2 acknowledgment and error-source allocation
helpers from ghes.c into ghes_cper.c. The logic is kept unchanged while
making the helpers reusable.

> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
> index f74fd5de34cc5..bda535224422d 100644
> --- a/drivers/acpi/apei/ghes.c
> +++ b/drivers/acpi/apei/ghes.c

[Severity: High]
This isn't a bug introduced by this patch, but while reviewing the GHES
codebase, I noticed a potential locking omission involving the ghes_devs
list.

Does the EDAC driver need to hold ghes_devs_mutex during initialization
and teardown?

Looking at drivers/edac/ghes_edac.c, ghes_edac_init() and ghes_edac_exit()
traverse the ghes_devs list locklessly:

drivers/edac/ghes_edac.c:ghes_edac_init() {
    ...
    list_for_each_entry_safe(g, g_tmp, ghes_devs, elist) {
        ghes_edac_register(g->dev);
    }
    ...
}

However, in drivers/acpi/apei/ghes.c, ghes_remove() deletes entries from
this list under the mutex:

drivers/acpi/apei/ghes.c:ghes_remove() {
    ...
    mutex_lock(&ghes_devs_mutex);
    list_del(&ghes->elist);
    mutex_unlock(&ghes_devs_mutex);
    ...
}

Could concurrent execution of module loading/unloading (e.g., modprobe
ghes_edac) and GHES platform device bind/unbind via sysfs cause linked
list corruption or a use-after-free?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260708-topics-ahmtib01-ras_ffh_arm_internal_review-v7-0-8b3a85216cef@arm.com?part=3