linux-kernel - Re: [PATCH] btrfs: fix memory leak when rejecting a non SINGLE data profile without an RST

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Message-ID: <87y0pmj4uc.fsf@>
Date: Tue, 07 Oct 2025 14:04:11 +0200
From: Miquel Sabaté Solà <mssola@...ola.com>
To: Johannes Thumshirn <Johannes.Thumshirn@....com>
Cc: "linux-btrfs@...r.kernel.org" <linux-btrfs@...r.kernel.org>,
  "clm@...com" <clm@...com>,  "dsterba@...e.com" <dsterba@...e.com>,
  "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] btrfs: fix memory leak when rejecting a non SINGLE data
 profile without an RST

Johannes Thumshirn @ 2025-10-07 11:21 GMT:

> On 10/7/25 1:05 PM, Miquel Sabaté Solà wrote:
>
>  Johannes Thumshirn @ 2025-10-07 10:13 GMT:
>
>
>
> Wouldn't it make more sense to only set "ret = -EINVAL" and run the rest
> of the functions cleanup? I.e. with your patch the chunk_map isn't freed
> as well.
>
>
> The short answer is that I wanted to keep the patch as minimal as
> possible while preserving the intent of the original code. From the
> original code (see commit 5906333cc4af ("btrfs: zoned: don't skip block
> group profile checks on conventional zones")), I get that the intent was
> to return as early as possible, so to not go through all the if
> statements below as they were not relevant on that case (that is, not
> just the one you mention where the cache->physical_map is
> freed). Falling through as you suggest would go into these if/else
> blocks, which I don't think is what we want to do.
>
> But it still sounds good that we should probably also free the chunk map
> as you say. Hence, maybe we could move the new "out_free:" label before
> the `if (!ret)` block right above where I've put it now. This way we
> ensure that the chunk map is freed, and we avoid going through the other
> if/else blocks which the aforementioned commit wanted to avoid.
>
> No it really should only be ret = -EINVAL without any new labels AFAICS.
>
> 1)  the alloc_offset vs zone_capacity check is still usable

I don't think so as the ret value will be changed from -EINVAL (as set
from the previous if block) to -EIO. I believe that the intent from the
aforementioned commit was to return an -EINVAL on this case.

Maybe the reviewers from commit 5906333cc4af ("btrfs: zoned: don't skip
block group profile checks on conventional zones") can shed some light
into this...

>
> 2) the check if we're post the WP is skipped as ret != 0
>
> 3) we're hitting the else path and freeing the chunk map.
>
>  As a last note, maybe for v2 I should add:
>
> Fixes: 5906333cc4af ("btrfs: zoned: don't skip block group profile checks on conventional zones")
>
> Correct

My email client detected your email as an HTML one. Is that so? Just as
a heads up for others as the reply format might look a bit funky :/

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