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=1793212005; b=hJ9zXGuncM9CgntcuaJtOMIu31ayOcTTqbQPWKJoEzaIvAmFhd+9kYG2UOGcpuqQRY0f Lyk9Z9Xvt0jshHQm65JlEQmuVdA9enX8K1P7CztRedUGfy310xYqTmnxVXI2qQdBMlZN1 4BHphH3pdWkj3dVo4B60S+SIUsTypTKb2AAAAeFtc9SHGDbOWfskzVqzOddKFFGeULyHa na4E3Aji0QF2ynbfOQsSWVL/5S1ROcRMHTsVQYiw0fqp9/Tj5nDJLCfvy8Mp5Y5RQIfBa UDIOZnj1qsUIJFY49Vwvf38qRs9i0G6YRJiT9EODrLBM7hv+KCEyIq64rcGIWL+PogQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793212005; 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=1+0mQqZzjr991ARcDMi3LhQ8e7r7EY69vJzDCCnRpUk=; b=xYjeWUCJ+QwLM0DkN8dAVBE7mlwHj8CwClz2BjKV1aRd6Pz03bXgmhZNVkgwk1Qdb/Ts 8UQoTplfAmqNpyrlDmGmkhgd18XJ32SgukC3JjScTdL0yJLm21Sf2l5WxLPF5ADRrspdc xF/7oYOu92OwUxnfv3HuW8j3RlzMAr4o/fHEvgCOPKD6VQMdnukv9VVHddQ7JkbG3A+9A Wb3p3E+Q4bitIv6N4f/rwbDlhK+/URZaENINvOiXOqOOIiAliU7GEZPzjFMzPqfE79Tvw XsVlQh+VdA2FcoyqYEPK0RJsgHTRiEKqlelAW8pgKaT8NbMPDL5wLa2TO3t+OJb1gxg== 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=VGgMxtkG; 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 25BAB606A31D; Wed, 28 Oct 2026 18:26:44 +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=VGgMxtkG Received: by smtp.kernel.org (Postfix) with ESMTPSA id 776191F01825; Wed, 28 Oct 2026 18:26:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793212004; bh=1+0mQqZzjr991ARcDMi3LhQ8e7r7EY69vJzDCCnRpUk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=VGgMxtkGBThad5VwdGNXjy/l//HbQqRMGqOQIcXg6OcVhwuaASxChNo21z1I6VLYc RRGnqq7XtWf1wRgqik4FEeej5L6BJJI9oZYCDRSnE81RRcg58ZveLxpaHzaejbQgm0 FGahYzHbn5i+LzSoPWzBMUm7xzmLVwoiwjIIId4k= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jarkko Sakkinen , Cen Zhang , David Howells Subject: [PATCH 5.15 566/571] keys: Protect the read method check against type removal Date: Wed, 28 Oct 2026 18:01:53 +0100 Message-ID: <20261028170021.465744873@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: Cen Zhang commit 925c84e3cc21caf09de92d9bcafab0147790debf upstream. keyctl_read_key() checks key->type->read without holding key->sem. A reference keeps the key alive, but does not pin the module containing its type. A surviving RxRPC key can therefore be read while AF_RXRPC is being unloaded: KEYCTL_READ task Module unload and key GC ---------------- ------------------------ lookup_user_key() permission / possession checks load key->type af_rxrpc_exit() unregister_key_type() GC: down_write(key->sem) GC: retype to key_type_dead GC: up_write(key->sem) unregister_key_type() returns free_module() read saved type's read member The final access can read freed module storage. The read invocation in __keyctl_read_key() is already protected by key->sem, but the earlier method check is outside that critical section. Move the method check into __keyctl_read_key(), after key_validate() and under its existing read hold on key->sem. The check and invocation then use the same protected type for length queries and every read retry. The GC cannot retype the key until the semaphore is released, and type unregistration waits for that GC pass before the module can be freed. Return -EOPNOTSUPP when validation succeeds and the type has no read method. A temporary buffer may now be allocated before this result; allocation and copying to userspace remain outside the semaphore. Assisted-by: LLM Cc: stable@vger.kernel.org # v5.10+ Fixes: d3ec10aa9581 ("KEYS: Don't write out to userspace while holding key semaphore") Suggested-by: Jarkko Sakkinen Signed-off-by: Cen Zhang Reviewed-by: Jarkko Sakkinen Reviewed-by: David Howells Link: https://lore.kernel.org/r/pm-key-management-objects-candidate-0010-v7-fc85721ff5cfb9e33ac6@gmail.com Signed-off-by: Jarkko Sakkinen Signed-off-by: Greg Kroah-Hartman --- security/keys/keyctl.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -808,8 +808,12 @@ static long __keyctl_read_key(struct key down_read(&key->sem); ret = key_validate(key); - if (ret == 0) - ret = key->type->read(key, buffer, buflen); + if (ret == 0) { + if (key->type->read) + ret = key->type->read(key, buffer, buflen); + else + ret = -EOPNOTSUPP; + } up_read(&key->sem); return ret; } @@ -863,11 +867,6 @@ long keyctl_read_key(key_serial_t keyid, /* the key is probably readable - now try to read it */ can_read_key: - if (!key->type->read) { - ret = -EOPNOTSUPP; - goto key_put_out; - } - if (!buffer || !buflen) { /* Get the key length from the read method */ ret = __keyctl_read_key(key, NULL, 0);