{"id":2222642,"url":"http://patchwork.ozlabs.org/api/1.2/patches/2222642/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-cifs-client/patch/20260413085957.77355-1-phx0fer@gmail.com/","project":{"id":12,"url":"http://patchwork.ozlabs.org/api/1.2/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":"<20260413085957.77355-1-phx0fer@gmail.com>","list_archive_url":null,"date":"2026-04-13T08:59:57","name":"smb: client: Fix integer underflow in receive_encrypted_read()","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"fe18e557a46327cef04b9c33352f986dff7418c4","submitter":{"id":93127,"url":"http://patchwork.ozlabs.org/api/1.2/people/93127/?format=json","name":"Dudu Lu","email":"phx0fer@gmail.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linux-cifs-client/patch/20260413085957.77355-1-phx0fer@gmail.com/mbox/","series":[{"id":499669,"url":"http://patchwork.ozlabs.org/api/1.2/series/499669/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-cifs-client/list/?series=499669","date":"2026-04-13T08:59:57","name":"smb: client: Fix integer underflow in receive_encrypted_read()","version":1,"mbox":"http://patchwork.ozlabs.org/series/499669/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2222642/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2222642/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=ZIdAzjIr;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c09:e001:a7::12fc:5321; helo=sto.lore.kernel.org;\n envelope-from=linux-cifs+bounces-10767-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=\"ZIdAzjIr\"","smtp.subspace.kernel.org;\n arc=none smtp.client-ip=209.85.214.176","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 sto.lore.kernel.org (sto.lore.kernel.org\n [IPv6:2600:3c09:e001:a7::12fc:5321])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fvLvs1bRpz1xtJ\n\tfor ; Mon, 13 Apr 2026 19:00:09 +1000 (AEST)","from smtp.subspace.kernel.org (conduit.subspace.kernel.org\n [100.90.174.1])\n\tby sto.lore.kernel.org (Postfix) with ESMTP id BFC2A300233A\n\tfor ; Mon, 13 Apr 2026 09:00:05 +0000 (UTC)","from localhost.localdomain (localhost.localdomain [127.0.0.1])\n\tby smtp.subspace.kernel.org (Postfix) with ESMTP id 1BDB93A874A;\n\tMon, 13 Apr 2026 09:00:04 +0000 (UTC)","from mail-pl1-f176.google.com (mail-pl1-f176.google.com\n [209.85.214.176])\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 DCEB53AC0DC\n\tfor ; Mon, 13 Apr 2026 09:00:02 +0000 (UTC)","by mail-pl1-f176.google.com with SMTP id\n d9443c01a7336-2b2494440f3so13843645ad.2\n for ;\n Mon, 13 Apr 2026 02:00:02 -0700 (PDT)","from gmail.com (69-172-89-235.static.imsbiz.com. 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If a malicious server sends a value smaller than\nread_rsp_size (sizeof(struct smb2_read_rsp), ~80 bytes), the unsigned\nsubtraction wraps to a very large value (~4GB). This value is then\npassed to netfs_alloc_folioq_buffer() and cifs_read_iter_from_socket(),\ncausing either:\n - A massive allocation attempt that fails with -ENOMEM (DoS)\n - Under extreme memory pressure, potential heap corruption\n\nThe existing validation in smb3_receive_transform() only checks\nthat pdu_length >= orig_len + sizeof(transform_hdr), which does\nnot prevent orig_len from being smaller than read_rsp_size.\n\nFix this by adding a check that OriginalMessageSize is at least\nread_rsp_size before the subtraction.\n\nSigned-off-by: Dudu Lu \n---\n fs/smb/client/smb2ops.c | 8 ++++++++\n 1 file changed, 8 insertions(+)","diff":"diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c\nindex 509fcea28a42..ca90f96052d4 100644\n--- a/fs/smb/client/smb2ops.c\n+++ b/fs/smb/client/smb2ops.c\n@@ -4943,6 +4943,14 @@ receive_encrypted_read(struct TCP_Server_Info *server, struct mid_q_entry **mid,\n \t\tgoto free_dw;\n \tserver->total_read += rc;\n \n+\tif (le32_to_cpu(tr_hdr->OriginalMessageSize) <\n+\t server->vals->read_rsp_size) {\n+\t\tcifs_server_dbg(VFS, \"OriginalMessageSize %u too small for read response (%u)\\n\",\n+\t\t\tle32_to_cpu(tr_hdr->OriginalMessageSize),\n+\t\t\tserver->vals->read_rsp_size);\n+\t\trc = -EINVAL;\n+\t\tgoto free_dw;\n+\t}\n \tlen = le32_to_cpu(tr_hdr->OriginalMessageSize) -\n \t\tserver->vals->read_rsp_size;\n \tdw->len = len;\n","prefixes":[]}