linux-kernel - RE: [PATCH v1 1/2] ACPI: NFIT: Fix memory leak, and local use of devm

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Message-ID: <652883fe10d38_780ef29459@dwillia2-xfh.jf.intel.com.notmuch>
Date:   Thu, 12 Oct 2023 16:40:46 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     Michal Wilczynski <michal.wilczynski@...el.com>,
        <linux-acpi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <nvdimm@...ts.linux.dev>
CC:     <rafael.j.wysocki@...el.com>, <andriy.shevchenko@...el.com>,
        <lenb@...nel.org>, <dan.j.williams@...el.com>,
        <vishal.l.verma@...el.com>, <ira.weiny@...el.com>,
        Michal Wilczynski <michal.wilczynski@...el.com>,
        "Andy Shevchenko" <andy.shevchenko@...il.com>
Subject: RE: [PATCH v1 1/2] ACPI: NFIT: Fix memory leak, and local use of
 devm_*()

Michal Wilczynski wrote:
> devm_*() family of functions purpose is managing memory attached to a
> device. So in general it should only be used for allocations that should
> last for the whole lifecycle of the device. This is not the case for
> acpi_nfit_init_interleave_set(). There are two allocations that are only
> used locally in this function. What's more - if the function exits on
> error path memory is never freed. It's still attached to dev and would
> be freed on device detach, so this leak could be called a 'local leak'.

This analysis is incorrect devm cleans up on driver ->probe() failure in
addition to ->remove(), and these error returns result in ->probe()
failures. No leak, i.e. this is not a fix.

The conversion to modern probe is ok if you want to resubmit that one
without this intervening change.