{"id":2224703,"url":"http://patchwork.ozlabs.org/api/patches/2224703/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-cifs-client/patch/20260417193317.315698-1-tristan@talencesecurity.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":"<20260417193317.315698-1-tristan@talencesecurity.com>","list_archive_url":null,"date":"2026-04-17T19:33:17","name":"[v2] ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"62bcdf4a5c9a4e287de0100d527313a75170b11b","submitter":{"id":93179,"url":"http://patchwork.ozlabs.org/api/people/93179/?format=json","name":"Tristan Madani","email":"tristmd@gmail.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linux-cifs-client/patch/20260417193317.315698-1-tristan@talencesecurity.com/mbox/","series":[{"id":500395,"url":"http://patchwork.ozlabs.org/api/series/500395/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-cifs-client/list/?series=500395","date":"2026-04-17T19:33:17","name":"[v2] ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment","version":2,"mbox":"http://patchwork.ozlabs.org/series/500395/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2224703/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2224703/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=Zfwpzdvd;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c0a:e001:db::12fc:5321; helo=sea.lore.kernel.org;\n envelope-from=linux-cifs+bounces-10895-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=\"Zfwpzdvd\"","smtp.subspace.kernel.org;\n arc=none smtp.client-ip=209.85.221.47","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 sea.lore.kernel.org (sea.lore.kernel.org\n [IPv6:2600:3c0a:e001:db::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 4fy4mx5Lb0z1yCv\n\tfor ; Sat, 18 Apr 2026 05:33:37 +1000 (AEST)","from smtp.subspace.kernel.org (conduit.subspace.kernel.org\n [100.90.174.1])\n\tby sea.lore.kernel.org (Postfix) with ESMTP id B145A3011C65\n\tfor ; Fri, 17 Apr 2026 19:33:26 +0000 (UTC)","from localhost.localdomain (localhost.localdomain [127.0.0.1])\n\tby smtp.subspace.kernel.org (Postfix) with ESMTP id 0E40832E126;\n\tFri, 17 Apr 2026 19:33:25 +0000 (UTC)","from mail-wr1-f47.google.com (mail-wr1-f47.google.com\n [209.85.221.47])\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 B1DFF389470\n\tfor ; Fri, 17 Apr 2026 19:33:21 +0000 (UTC)","by mail-wr1-f47.google.com with SMTP id\n ffacd0b85a97d-43cfd1f9fd1so660512f8f.3\n for ;\n Fri, 17 Apr 2026 12:33:20 -0700 (PDT)","from debian.. 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The bounds check on buf_free_len is performed\nbefore the value memcpy, but the alignment memset fires unconditionally\nafterward with no check on remaining space.\n\nWhen the EA value exactly fills the remaining buffer (buf_free_len == 0\nafter value subtraction), the alignment memset writes 1-3 NUL bytes\npast the buf_free_len boundary. In compound requests where the response\nbuffer is shared across commands, the first command (e.g., READ) can\nconsume most of the buffer, leaving a tight remainder for the QUERY_INFO\nEA response. The alignment memset then overwrites past the physical\nkvmalloc allocation into adjacent kernel heap memory.\n\nAdd a bounds check before the alignment memset to ensure buf_free_len\ncan accommodate the padding bytes.\n\nThis is the same bug pattern fixed by commit beef2634f81f (\"ksmbd: fix\npotencial OOB in get_file_all_info() for compound requests\") and\ncommit fda9522ed6af (\"ksmbd: fix OOB write in QUERY_INFO for compound\nrequests\"), both of which added bounds checks before unconditional\nwrites in QUERY_INFO response handlers.\n\nCc: stable@vger.kernel.org\nFixes: e2b76ab8b5c9 (\"ksmbd: add support for read compound\")\nSigned-off-by: Tristan Madani \n---\n fs/smb/server/smb2pdu.c | 2 ++\n 1 file changed, 2 insertions(+)","diff":"diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c\nindex ee32e61b6d3c7..407173d2175af 100644\n--- a/fs/smb/server/smb2pdu.c\n+++ b/fs/smb/server/smb2pdu.c\n@@ -4821,6 +4821,8 @@ static int smb2_get_ea(struct ksmbd_work *work, struct ksmbd_file *fp,\n \t\t/* align next xattr entry at 4 byte bundary */\n \t\talignment_bytes = ((next_offset + 3) & ~3) - next_offset;\n \t\tif (alignment_bytes) {\n+\t\t\tif (buf_free_len < alignment_bytes)\n+\t\t\t\tbreak;\n \t\t\tmemset(ptr, '\\0', alignment_bytes);\n \t\t\tptr += alignment_bytes;\n \t\t\tnext_offset += alignment_bytes;\n","prefixes":["v2"]}