From: sashiko-bot@kernel.org
Cc: linux-security-module@vger.kernel.org
Subject: Re: [PATCH] KEYS: Fix add_key() race with keyring restriction
Date: Wed, 30 Sep 2026 04:28:06 +0000 [thread overview]
Message-ID: <20260930042806.AABFB1F000FF@smtp.kernel.org> (raw)
In-Reply-To: <20260930041802.6114-1-tjdqudcks0424@naver.com>
> From: 성병찬 <tjdqudcks0424@naver.com>
>
> __key_create_or_update() snapshots keyring->restrict_link before taking
> the destination keyring's semaphore. keyring_restrict() installs a
> restriction while holding that semaphore.
>
> This allows a writer to observe no restriction, wait for the keyring
> owner to install a reject-all restriction and return successfully, and
> then link a key using the stale NULL snapshot. The writer only needs
> write permission on the destination keyring.
>
> Move the restrict_link read after __key_link_lock() and
> __key_link_begin(). The read and the subsequent restriction check are
> then serialized with restriction installation by keyring->sem.
>
> The race was reproduced on v7.2.8 in 19 executions where restriction
> installation returned before the link completed. All 19 linked the key
> despite the reject-all restriction. With this change, 312 executions
> reached the same ordering and every add_key() call failed with -EPERM.
>
> The issue was found by manual concurrency analysis assisted by AI-based
> analysis and independently verified with a QEMU reproducer and kernel
> instrumentation.
>
> Fixes: 5ac7eace2d00 ("KEYS: Add a facility to restrict new links into a keyring")
> Cc: stable@vger.kernel.org
> Signed-off-by: 성병찬 <tjdqudcks0424@naver.com>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review · https://sashiko.dev/#/patchset/20260930041802.6114-1-tjdqudcks0424@naver.com?part=1
next prev parent reply other threads:[~2026-09-30 4:28 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-30 4:18 [PATCH] KEYS: Fix add_key() race with keyring restriction tjdqudcks0424
2026-09-30 4:28 ` sashiko-bot [this message]
2026-10-02 3:18 ` Jarkko Sakkinen
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