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=1793207408; b=isJBzj0llIfy3Fjj0ZSRbVQuDg1qmfV0NWZjd8mHNF2oy8Oi274spzmbZ03RjHPooge1 0d06n1OZE6B1V4Ljdr99dDyui7fGlzlvXzNiu6Rvt1FGIXKb0rKC5Jp2KecrioHlrHBeJ ZEpksiVNSiRVHq7bPnOB2kntJlaa5EOcFlbo5n6/SIGHSiut1HJ9VpZ/VtNi0zuGDt2Kc ASaQsRohw8O8ONBdzFa9tjdTqAcCeRAUBEadu49lEiahiycKtADv8ZV3NOFviZnBTf0Uk FnYyzi/fqWlUFY+XL1wK0ftkHdB+mav5VqwrO5yCIzMwoUwYgqKM50AgP+KPoX7nxoA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793207408; 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=/cTGbpp/PqgpxUyzY8RTabNN5UTElqcifl3hPV+OpMU=; b=zd1oiQjg2e4TDLpHxscTyYzVKUpWkaa2ORIqudckC6heg9RIfISNd2woDYizckNkXPM3 54kIzM9ho+kP1GMPpc85lyk0xqLmf/V2EELKrP8CMS8EkLmll84UgS+r3AuA8+VSZvA0F 1r9poa2GduGP2gD1HTwKJzbTyWnT2KPQcMHqwjNG4zhb0Og1z7CAHsekKNyFJiLos955v FsntgS9aWWxs7MoBnPMEGdO2GwnW2aJwDVSTKOYaYvxNTw9eaLAFCHzOUzPSGSSWZzLkJ f1qABFIBtrV4V0qqw6kjbOA/5uZR4IwtWwO0LBSAcaurWMoO2ATyuiOvqzcqZI91IwA== 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=p+wtfm0C; 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 620EA606A31A; Wed, 28 Oct 2026 17:10:08 +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=p+wtfm0C Received: by smtp.kernel.org (Postfix) with ESMTPSA id B46E11F01829; Wed, 28 Oct 2026 17:10:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793207408; bh=/cTGbpp/PqgpxUyzY8RTabNN5UTElqcifl3hPV+OpMU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=p+wtfm0C+ncTW/irh4WTqlnrc/OY0zqOjKiq8biJ4VhBNjfH0LpCrtm6qMoioT0rT fhLg9YA8R9B2AFDPpksE5wjAgH+iFHInP5uKHUtKr6wuzYUQSJg0pFrl39sX/PoAVb j4gEgU640ZLB03Eq1ZIOEJcchAS554QQfY8Xg9RI= 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 7.2 74/88] keys: Protect the read method check against type removal Date: Wed, 28 Oct 2026 18:00:22 +0100 Message-ID: <20261028165943.858015842@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028165942.107695352@linuxfoundation.org> References: <20261028165942.107695352@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 7.2-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);