{"id":2223243,"url":"http://patchwork.ozlabs.org/api/patches/2223243/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-cifs-client/patch/20260414191533.1467353-2-michael.bommarito@gmail.com/","project":{"id":12,"url":"http://patchwork.ozlabs.org/api/projects/12/?format=json","name":"Linux CIFS Client","link_name":"linux-cifs-client","list_id":"linux-cifs.vger.kernel.org","list_email":"linux-cifs@vger.kernel.org","web_url":"","scm_url":"","webscm_url":"","list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260414191533.1467353-2-michael.bommarito@gmail.com>","list_archive_url":null,"date":"2026-04-14T19:15:31","name":"[1/3] ksmbd: cap response sizes in ipc_validate_msg()","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"c1d344feb6683b1de30441d9d24ae4e99f13b313","submitter":{"id":93078,"url":"http://patchwork.ozlabs.org/api/people/93078/?format=json","name":"Michael Bommarito","email":"michael.bommarito@gmail.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linux-cifs-client/patch/20260414191533.1467353-2-michael.bommarito@gmail.com/mbox/","series":[{"id":499887,"url":"http://patchwork.ozlabs.org/api/series/499887/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-cifs-client/list/?series=499887","date":"2026-04-14T19:15:31","name":"ksmbd: harden IPC response arithmetic and ACE walk","version":1,"mbox":"http://patchwork.ozlabs.org/series/499887/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2223243/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2223243/checks/","tags":{},"related":[],"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-cifs@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20251104 header.b=CnBwQcDu;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c04:e001:36c::12fc:5321; helo=tor.lore.kernel.org;\n envelope-from=linux-cifs+bounces-10820-incoming=patchwork.ozlabs.org@vger.kernel.org;\n receiver=patchwork.ozlabs.org)","smtp.subspace.kernel.org;\n\tdkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com\n header.b=\"CnBwQcDu\"","smtp.subspace.kernel.org;\n arc=none smtp.client-ip=209.85.219.47","smtp.subspace.kernel.org;\n dmarc=pass (p=none dis=none) header.from=gmail.com","smtp.subspace.kernel.org;\n spf=pass smtp.mailfrom=gmail.com"],"Received":["from tor.lore.kernel.org (tor.lore.kernel.org\n [IPv6:2600:3c04:e001:36c::12fc:5321])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519 server-signature ECDSA (secp384r1) server-digest SHA384)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fwDX42CgMz1y2d\n\tfor ; Wed, 15 Apr 2026 05:16:04 +1000 (AEST)","from smtp.subspace.kernel.org (conduit.subspace.kernel.org\n [100.90.174.1])\n\tby tor.lore.kernel.org (Postfix) with ESMTP id 534C13046F2A\n\tfor ; Tue, 14 Apr 2026 19:15:59 +0000 (UTC)","from localhost.localdomain (localhost.localdomain [127.0.0.1])\n\tby smtp.subspace.kernel.org (Postfix) with ESMTP id 89DA32D12F3;\n\tTue, 14 Apr 2026 19:15:56 +0000 (UTC)","from mail-qv1-f47.google.com (mail-qv1-f47.google.com\n [209.85.219.47])\n\t(using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits))\n\t(No client certificate requested)\n\tby smtp.subspace.kernel.org (Postfix) with ESMTPS id 3FE49282F25\n\tfor ; Tue, 14 Apr 2026 19:15:55 +0000 (UTC)","by mail-qv1-f47.google.com with SMTP id\n 6a1803df08f44-8a3b0242631so68778066d6.3\n for ;\n Tue, 14 Apr 2026 12:15:55 -0700 (PDT)","from server0 (c-68-48-65-54.hsd1.mi.comcast.net. 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Three cases can overflow:\n\n KSMBD_EVENT_RPC_REQUEST:\n msg_sz = sizeof(struct ksmbd_rpc_command) + resp->payload_sz;\n KSMBD_EVENT_SHARE_CONFIG_REQUEST:\n msg_sz = sizeof(struct ksmbd_share_config_response) +\n resp->payload_sz;\n KSMBD_EVENT_LOGIN_REQUEST_EXT:\n msg_sz = sizeof(struct ksmbd_login_response_ext) +\n resp->ngroups * sizeof(gid_t);\n\nresp->payload_sz is __u32 and resp->ngroups is __s32. Each addition\ncan wrap in unsigned int; the multiplication by sizeof(gid_t) mixes\nsigned and size_t, so a negative ngroups is converted to SIZE_MAX\nbefore the multiply. A wrapped value of msg_sz that happens to\nequal entry->msg_sz bypasses the size check on the next line, and\ndownstream consumers (smb2pdu.c:6742 memcpy using rpc_resp->payload_sz,\nkmemdup in ksmbd_alloc_user using resp_ext->ngroups) then trust the\nunverified length.\n\nThis is the response-side analogue of aab98e2dbd64 (\"ksmbd: fix\ninteger overflows on 32 bit systems\"), which hardened the request\nside by bounding attacker-controlled lengths against the existing\nKSMBD_IPC_MAX_PAYLOAD / NGROUPS_MAX caps. Apply the same caps on\nthe response side: reject resp->payload_sz > KSMBD_IPC_MAX_PAYLOAD\nfor RPC_REQUEST and SHARE_CONFIG_REQUEST, and reject resp->ngroups\noutside the signed [0, NGROUPS_MAX] range for LOGIN_REQUEST_EXT.\nWith those caps the subsequent additions and multiplication are\nbounded well below UINT_MAX.\n\nFixes: 0626e6641f6b (\"cifsd: add server handler for central processing and tranport layers\")\nCc: stable@vger.kernel.org\nAssisted-by: Claude:claude-opus-4-6\nAssisted-by: Codex:gpt-5-4\nSigned-off-by: Michael Bommarito \n---\n fs/smb/server/transport_ipc.c | 7 ++++++-\n 1 file changed, 6 insertions(+), 1 deletion(-)\n\n--\n2.53.0","diff":"diff --git a/fs/smb/server/transport_ipc.c b/fs/smb/server/transport_ipc.c\n--- a/fs/smb/server/transport_ipc.c\n+++ b/fs/smb/server/transport_ipc.c\n@@ -497,6 +497,8 @@ static int ipc_validate_msg(struct ipc_msg_table_entry *entry)\n \t{\n \t\tstruct ksmbd_rpc_command *resp = entry->response;\n\n+\t\tif (resp->payload_sz > KSMBD_IPC_MAX_PAYLOAD)\n+\t\t\treturn -EINVAL;\n \t\tmsg_sz = sizeof(struct ksmbd_rpc_command) + resp->payload_sz;\n \t\tbreak;\n \t}\n@@ -513,7 +515,8 @@ static int ipc_validate_msg(struct ipc_msg_table_entry *entry)\n \t\tstruct ksmbd_share_config_response *resp = entry->response;\n\n \t\tif (resp->payload_sz) {\n-\t\t\tif (resp->payload_sz < resp->veto_list_sz)\n+\t\t\tif (resp->payload_sz < resp->veto_list_sz ||\n+\t\t\t resp->payload_sz > KSMBD_IPC_MAX_PAYLOAD)\n \t\t\t\treturn -EINVAL;\n\n \t\t\tmsg_sz = sizeof(struct ksmbd_share_config_response) +\n@@ -526,6 +529,8 @@ static int ipc_validate_msg(struct ipc_msg_table_entry *entry)\n \t\tstruct ksmbd_login_response_ext *resp = entry->response;\n\n \t\tif (resp->ngroups) {\n+\t\t\tif (resp->ngroups < 0 || resp->ngroups > NGROUPS_MAX)\n+\t\t\t\treturn -EINVAL;\n \t\t\tmsg_sz = sizeof(struct ksmbd_login_response_ext) +\n \t\t\t\t\tresp->ngroups * sizeof(gid_t);\n \t\t}\n","prefixes":["1/3"]}