From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4C404366DD6 for ; Thu, 19 Mar 2026 15:02:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773932568; cv=none; b=j3/OverMEr0nAKxFnedXGKa1C+nc9QUSAyRbKTa7a1t0ze5hS7xczvuiZTvBoaZUinSkCQkytTaN7UjvtSQ7szLThwNoWoxBTMoEWkjLNV5jZ7knFXWKz5KDpRVS9QzqTxn/+VR6U33i7OwrWePFVAePivmZYbmJ9dZSpo4vUe4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773932568; c=relaxed/simple; bh=GLd4qfXuiZlmFgoBnEIpAEMmRw0SwUkeo0/6dC1W5Lg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=dDYXDvQBHtxcVSroJE4TekuJm37NAqvz8Mbn8oxYrrnW+/dV7Pt/me5rSHqCwzeeu2EIkB1I3YisL2BTpKJ4rMMim6vRpnxxna/wXqcNMEhwP9qPbd/hCr2SKVWrKY8u4WFUim4YYUhSJELa4Ee5cO84PQ498KfbLcB2jFiLe1Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=FHBCrzlS; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="FHBCrzlS" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1773932566; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=qeCoRrsqHiEQgKw5Tn8Q3ISupxkgu6z3xAFPorUcwac=; b=FHBCrzlS9rjGlkRO+TWYRqluTaDelpFVg2HpTr2HKQBfhY6qFCIIFq991XHmNdRay2gmov FmH3xnKAjA3FIGBWiCxXEQsFbvSr9sqertNXt/qwlEW5zNLWovuFeDbKGHGbxljvGFpgAs Ue29ys9MekScFJj2c1dBwfPHYySZjcY= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-441-9gM4NXuRN8uRQsBEk0ixxQ-1; Thu, 19 Mar 2026 11:02:43 -0400 X-MC-Unique: 9gM4NXuRN8uRQsBEk0ixxQ-1 X-Mimecast-MFC-AGG-ID: 9gM4NXuRN8uRQsBEk0ixxQ_1773932561 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7C7141800283; Thu, 19 Mar 2026 15:02:40 +0000 (UTC) Received: from warthog.procyon.org.com (unknown [10.45.224.65]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 81A991800107; Thu, 19 Mar 2026 15:02:36 +0000 (UTC) From: David Howells To: netdev@vger.kernel.org Cc: David Howells , Marc Dionne , Jakub Kicinski , "David S. Miller" , Eric Dumazet , Paolo Abeni , linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org, Oleh Konko , Jeffrey Altman , Simon Horman , stable@kernel.org Subject: [PATCH net 1/5] rxrpc: Fix RxGK token loading to check bounds Date: Thu, 19 Mar 2026 15:01:41 +0000 Message-ID: <20260319150150.4189381-2-dhowells@redhat.com> In-Reply-To: <20260319150150.4189381-1-dhowells@redhat.com> References: <20260319150150.4189381-1-dhowells@redhat.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 From: Oleh Konko rxrpc_preparse_xdr_yfs_rxgk() reads the raw key length and ticket length from the XDR token as u32 values and passes each through round_up(x, 4) before using the rounded value for validation and allocation. When the raw length is >= 0xfffffffd, round_up() wraps to 0, so the bounds check and kzalloc both use 0 while the subsequent memcpy still copies the original ~4 GiB value, producing a heap buffer overflow reachable from an unprivileged add_key() call. Fix this by: (1) Rejecting raw key lengths above AFSTOKEN_GK_KEY_MAX and raw ticket lengths above AFSTOKEN_GK_TOKEN_MAX before rounding, consistent with the caps that the RxKAD path already enforces via AFSTOKEN_RK_TIX_MAX. (2) Sizing the flexible-array allocation from the validated raw key length via struct_size_t() instead of the rounded value. (3) Caching the raw lengths so that the later field assignments and memcpy calls do not re-read from the token, eliminating a class of TOCTOU re-parse. The control path (valid token with lengths within bounds) is unaffected. Fixes: 0ca100ff4df6 ("rxrpc: Add YFS RxGK (GSSAPI) security class") Signed-off-by: Oleh Konko Signed-off-by: David Howells Reviewed-by: Jeffrey Altman cc: Marc Dionne cc: Eric Dumazet cc: "David S. Miller" cc: Jakub Kicinski cc: Paolo Abeni cc: Simon Horman cc: linux-afs@lists.infradead.org cc: netdev@vger.kernel.org cc: stable@kernel.org --- net/rxrpc/key.c | 30 +++++++++++++++++------------- 1 file changed, 17 insertions(+), 13 deletions(-) diff --git a/net/rxrpc/key.c b/net/rxrpc/key.c index 85078114b2dd..c96e1d8f4845 100644 --- a/net/rxrpc/key.c +++ b/net/rxrpc/key.c @@ -13,6 +13,7 @@ #include #include #include +#include #include #include #include @@ -171,7 +172,7 @@ static int rxrpc_preparse_xdr_yfs_rxgk(struct key_preparsed_payload *prep, size_t plen; const __be32 *ticket, *key; s64 tmp; - u32 tktlen, keylen; + size_t raw_keylen, raw_tktlen, keylen, tktlen; _enter(",{%x,%x,%x,%x},%x", ntohl(xdr[0]), ntohl(xdr[1]), ntohl(xdr[2]), ntohl(xdr[3]), @@ -181,18 +182,22 @@ static int rxrpc_preparse_xdr_yfs_rxgk(struct key_preparsed_payload *prep, goto reject; key = xdr + (6 * 2 + 1); - keylen = ntohl(key[-1]); - _debug("keylen: %x", keylen); - keylen = round_up(keylen, 4); + raw_keylen = ntohl(key[-1]); + _debug("keylen: %zx", raw_keylen); + if (raw_keylen > AFSTOKEN_GK_KEY_MAX) + goto reject; + keylen = round_up(raw_keylen, 4); if ((6 * 2 + 2) * 4 + keylen > toklen) goto reject; ticket = xdr + (6 * 2 + 1 + (keylen / 4) + 1); - tktlen = ntohl(ticket[-1]); - _debug("tktlen: %x", tktlen); - tktlen = round_up(tktlen, 4); + raw_tktlen = ntohl(ticket[-1]); + _debug("tktlen: %zx", raw_tktlen); + if (raw_tktlen > AFSTOKEN_GK_TOKEN_MAX) + goto reject; + tktlen = round_up(raw_tktlen, 4); if ((6 * 2 + 2) * 4 + keylen + tktlen != toklen) { - kleave(" = -EKEYREJECTED [%x!=%x, %x,%x]", + kleave(" = -EKEYREJECTED [%zx!=%x, %zx,%zx]", (6 * 2 + 2) * 4 + keylen + tktlen, toklen, keylen, tktlen); goto reject; @@ -206,7 +211,7 @@ static int rxrpc_preparse_xdr_yfs_rxgk(struct key_preparsed_payload *prep, if (!token) goto nomem; - token->rxgk = kzalloc(sizeof(*token->rxgk) + keylen, GFP_KERNEL); + token->rxgk = kzalloc(struct_size_t(struct rxgk_key, _key, raw_keylen), GFP_KERNEL); if (!token->rxgk) goto nomem_token; @@ -221,9 +226,9 @@ static int rxrpc_preparse_xdr_yfs_rxgk(struct key_preparsed_payload *prep, token->rxgk->enctype = tmp = xdr_dec64(xdr + 5 * 2); if (tmp < 0 || tmp > UINT_MAX) goto reject_token; - token->rxgk->key.len = ntohl(key[-1]); + token->rxgk->key.len = raw_keylen; token->rxgk->key.data = token->rxgk->_key; - token->rxgk->ticket.len = ntohl(ticket[-1]); + token->rxgk->ticket.len = raw_tktlen; if (token->rxgk->endtime != 0) { expiry = rxrpc_s64_to_time64(token->rxgk->endtime); @@ -236,8 +241,7 @@ static int rxrpc_preparse_xdr_yfs_rxgk(struct key_preparsed_payload *prep, memcpy(token->rxgk->key.data, key, token->rxgk->key.len); /* Pad the ticket so that we can use it directly in XDR */ - token->rxgk->ticket.data = kzalloc(round_up(token->rxgk->ticket.len, 4), - GFP_KERNEL); + token->rxgk->ticket.data = kzalloc(tktlen, GFP_KERNEL); if (!token->rxgk->ticket.data) goto nomem_yrxgk; memcpy(token->rxgk->ticket.data, ticket, token->rxgk->ticket.len);