From: Florian Westphal <fw@strlen.de>
To: Kamil Duljas <kamil.duljas@gmail.com>
Cc: Jakub Kicinski <kuba@kernel.org>,
"David S . Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>, Jiri Pirko <jiri@resnulli.us>,
Johannes Berg <johannes@sipsolutions.net>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] genetlink: Prevent memory leak when krealloc fail
Date: Sat, 18 Nov 2023 13:02:35 +0100 [thread overview]
Message-ID: <20231118120235.GA30289@breakpoint.cc> (raw)
In-Reply-To: <20231118113357.1999-1-kamil.duljas@gmail.com>
Kamil Duljas <kamil.duljas@gmail.com> wrote:
> genl_allocate_reserve_groups() allocs new memory in while loop
> but if krealloc fail, the memory allocated by kzalloc is not freed.
> It seems allocated memory is unnecessary when the function
> returns -ENOMEM
Why should it be free'd? mc_groups is not a local variable.
> new_groups = krealloc(mc_groups, nlen,
> GFP_KERNEL);
> - if (!new_groups)
> + if (!new_groups) {
> + kfree(mc_groups);
> return -ENOMEM;
> + }
How did you test this? AFAICS this results in use-after-free for every
access to mc_groups after this error path is taken.
Existing code looks correct, we can't grow mc_groups and return an
error.
next prev parent reply other threads:[~2023-11-18 12:02 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-18 11:33 [PATCH] genetlink: Prevent memory leak when krealloc fail Kamil Duljas
2023-11-18 12:02 ` Florian Westphal [this message]
2023-11-18 13:27 ` Kamil Duljas
2023-11-18 13:42 ` Florian Westphal
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