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=1793211994; b=SWcNEnMjjQcd6b+1oCYEzoyjEV6Y4Em1qRBgbjVC8xE15ngJsiOA7jwIPIcLAKv6u4HU 3ISxJpvRnwG7v6wYBl61pgWTxqQ53J1FNy88F2duyMJQKIzCHN78JpYGFiLEU2IiSkJHe eQrFkqmTI2tIYYET7DGnr6CM2SELwPiZItNgH9eNpdYBAUEQMvEF10FLfdk5AxEG7bu9A 5DG7vJq8C7dyuKvKC/YlNEvetf0mYI340JtwlMCzmQNRKIVDk4g8CvKkuQerlogsn1tn/ p+MNDaDGPXiOYPskMaAgFfoISU+SMBH+qpFgdD4kh98OZUuNRv8Pw/It5ZGiHfHuEJg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793211994; 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=IL84w4uXbdyoqeIxkreDArHwoxvUXKTcX3Sk2+6rFfM=; b=NB+IWoWBS81Z4SA144x/bZqajucwfvT54OhOCQAcuK5o7T4pFBS1tWA4Px+SsrkNCq2t O3M524T9J7DNwz52g5V/oiTXJg2lBr3xalXOKvkTRtYhBNuOlYm01g3gdF7jKRfA4SGxQ IW2YRInJZqYgwm1skYJWmeH9o6sX2ZVgEkk6gt5vyc7e9yKG/ntNnSIE8zW8XlpnWKbVv Rqmk67hEeNvpfX0atCczSXJLkfsUNRFSFt6sboQwaHNpUEHgwO3dF58kNBhzfCPfy8jpH fqRLCTb4dNQrjwkGQjW08cmTT69ZEEB6xuK60k2KmYRKLmBtY1hRP2i2V6HXHddtUBg== 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=SxstBXba; 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 7DCE6606A31D; Wed, 28 Oct 2026 18:26:34 +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=SxstBXba Received: by smtp.kernel.org (Postfix) with ESMTPSA id C9EF61F01825; Wed, 28 Oct 2026 18:26:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793211994; bh=IL84w4uXbdyoqeIxkreDArHwoxvUXKTcX3Sk2+6rFfM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=SxstBXba5XbFDrnVYZUCoN1vLjNyxcaBSjp0ZPKkFeXEi+Bwuw4Azhy52vnoOVw/p NQUNul6Lt7Wi1BVQ0Ly6MvaqC2Gl0C5HVyPMKS8oURvo9tolK81c56FBZyoq1evXuQ ecbiFWaJnQ058RpN8ShvBiAnvxLGOYkNRfbwys68= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Cen Zhang , Jarkko Sakkinen Subject: [PATCH 5.15 563/571] keys: Check the authorization payload in process keyring searches Date: Wed, 28 Oct 2026 18:01:50 +0100 Message-ID: <20261028170021.393202088@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 0a0ec45bf577a9b4d4960567f20d3877ef480de9 upstream. An authorization payload and its saved credentials must remain valid while search_process_keyrings_rcu() searches the requestor's keyrings. The function validates the authorization key, then separately loads payload.data[0] and unconditionally reads rka->cred. Validation does not prevent request_key_auth_revoke() from clearing the payload. A request-key helper can assume authority and fork a descendant that inherits the authorization key. If the descendant misses in its own keyrings, it falls back to the saved requestor credentials. Successful target instantiation invalidates the authorization key without clearing the payload. After the helper exits, UMH_WAIT_PROC returns to the requester, which calls complete_request_key() and revokes that key. With the descendant paused after validation, the paths can interleave as follows: 1. The descendant enters search_process_keyrings_rcu() under RCU and key_validate() succeeds. 2. The helper instantiates the target, invalidates the authorization key, and exits. 3. The requester resumes from UMH_WAIT_PROC, calls complete_request_key(), and revokes the authorization key. request_key_auth_revoke() sets its payload pointer to NULL. 4. The descendant loads NULL and dereferences rka->cred. This NULL dereference can oops the kernel. RCU delays payload disposal but does not prevent the pointer from being cleared. Load the payload with dereference_key_rcu() and require a non-NULL result before validating the authorization key and searching its saved credentials. A non-NULL payload and its credentials remain alive for the caller's RCU read-side section; a cleared payload skips the fallback search and follows the existing error selection. KASAN report as below: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f] RIP: 0010:search_process_keyrings_rcu+0x32b/0x790 Cc: stable@vger.kernel.org Fixes: e59428f721ee ("keys: Move the RCU locks outwards from the keyring search functions") Assisted-by: LLM Signed-off-by: Cen Zhang Reviewed-by: Jarkko Sakkinen Link: https://lore.kernel.org/r/pm-key-management-objects-candidate-0004-v3-598361863b76bc25d58d@gmail.com Signed-off-by: Jarkko Sakkinen Signed-off-by: Greg Kroah-Hartman --- security/keys/process_keys.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) --- a/security/keys/process_keys.c +++ b/security/keys/process_keys.c @@ -556,9 +556,8 @@ key_ref_t search_process_keyrings_rcu(st ) { const struct cred *cred = ctx->cred; - if (key_validate(cred->request_key_auth) == 0) { - rka = ctx->cred->request_key_auth->payload.data[0]; - + rka = dereference_key_rcu(cred->request_key_auth); + if (rka && key_validate(cred->request_key_auth) == 0) { //// was search_process_keyrings() [ie. recursive] ctx->cred = rka->cred; key_ref = search_cred_keyrings_rcu(ctx);