From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793212007; b=ejgPj1ggURFd3W+outFkjv7yPsTqPyxNt0rKtO5/cCp69ZkfdeKgN79hXM0tRt4sHKK7 KqS/2E1Sn5rteKa2EzScs8iALgwOsxeLQO4Xy/JG32kvKxrr2cwyyA35cEjoh9+u+gTqh GDCglYStnbDQ0p0jTDleZXhOovUT2KyzqHxeZ9P0WJehaU5Wa8auriELWcxOVbGLhj+tS swrtijGEanqLKif6iZ7DOQMZiO3qhGaVLDysLFsUWx4ecQ0y2CHBAkarC1ypJZL5tFPzk KXqpBrfevVv/1bs3xe5aYioyxLBEPonaTILQhqvnhF49Jx+IiekBUgONZuKvh5T+9yA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793212007; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=WjAqw5V9ITy5vxAalGeJDlWWbZRZNFOLbH7qxFbX9jE=; b=G6X07GqOWk+T8kFI8+EyEobhB8kLXiSvFV9F/1Zha1LRdGcc3bQOtqSHaRLIpMtLFzoU eXmLAsLX5/KOV8W/L8n4ZLqLlHQGrzzwhVPhQJ7gTnvuwvGJ9KFYoHoGXF3fpK4vhQCWM XHyk6ZZIQTNcx3ZBEJOPXTfsHavlgGuHphe/UwRmalFCUN6kyn0/GOi+xX+JzOawOnkwH h7AusjeFQQK1Mar/NuRVNA7nKr9MPvukszfzD3n5sGGH1SowkV+YyBUmPBUEBYGeYJLFl 387I8QzdAX4786w+qn0GYD3cU58AzTgMXGg39tSWYWfh5riOEX2Ce6Uphslwt3PIwJg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=t8nokXAs; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3120E606A31E; Wed, 28 Oct 2026 18:26:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=t8nokXAs Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4C4CC1F01825; Wed, 28 Oct 2026 18:26:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793212006; bh=WjAqw5V9ITy5vxAalGeJDlWWbZRZNFOLbH7qxFbX9jE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=t8nokXAshMF7v2mbJ71vVY9uJ26VRL+hU3ALC8fBaInMgZWO3bavYreoERhrcm4y+ ZlE4ZwbgajSRzdaUr10D0NZNOwKaWjZVI5EI7WMB6tAe8YufXKfCtQqnKLXfWaqx3g 1SBo54olpnlnlcGDXZ14EcMx6y3V8ifkLF06wk1o= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jarkko Sakkinen , Adrian Martinez Subject: [PATCH 5.15 567/571] KEYS: Fix key_reject_and_link() race with keyring restriction Date: Wed, 28 Oct 2026 18:01:54 +0100 Message-ID: <20261028170021.490797922@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170008.009143722@linuxfoundation.org> References: <20261028170008.009143722@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Adrian Martinez commit 0b157166e612b70f98a332b6c7be7eac6f8e9593 upstream. The restrict_link check in key_reject_and_link() is done before taking the keyring semaphore, racing with a concurrent keyring_restrict() that installs the restriction while holding the semaphore in write mode. Move the check to after __key_link_lock(), so it is done under the semaphore, matching the pattern used in __key_create_or_update(). Cc: stable@vger.kernel.org Fixes: 5ac7eace2d00 ("KEYS: Add a facility to restrict new links into a keyring") Reviewed-by: Jarkko Sakkinen Signed-off-by: Adrian Martinez Link: https://lore.kernel.org/r/CACO1+RT+m==BY+ZPkE+fo536D0qu3wog4xE1dfuXQ56g+=Qv=A@mail.gmail.com Signed-off-by: Jarkko Sakkinen Signed-off-by: Greg Kroah-Hartman --- security/keys/key.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) --- a/security/keys/key.c +++ b/security/keys/key.c @@ -586,11 +586,18 @@ int key_reject_and_link(struct key *key, ret = -EBUSY; if (keyring) { - if (keyring->restrict_link) - return -EPERM; - link_ret = __key_link_lock(keyring, &key->index_key); if (link_ret == 0) { + /* + * Check the restriction under the keyring semaphore. + * keyring_restrict() installs it while holding the + * semaphore, so testing it beforehand races with a + * concurrent restriction install. + */ + if (keyring->restrict_link) { + __key_link_end(keyring, &key->index_key, edit); + return -EPERM; + } link_ret = __key_link_begin(keyring, &key->index_key, &edit); if (link_ret < 0) __key_link_end(keyring, &key->index_key, edit);