From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qk1-f180.google.com (mail-qk1-f180.google.com [209.85.222.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AF661272803 for ; Fri, 10 Jul 2026 02:31:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.222.180 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783650709; cv=none; b=TPYNeMOIUznoTFga5w+o2XFSOX8iuK+bjogKDQYq++KPDmVn44nfc5hmtmQBGDa4eGhtB9oexztfmcKWwzyGWEZT69KvL4LPZgiaK5S37yP19j3rh2op364wIRaLML1tEiJO2STzevkzaNMYtdKNWIDHlMsEWIjlzMUmdNhrei4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783650709; c=relaxed/simple; bh=DLEOYtg6pX0wN99muAS2Kb4y9kiaFJu7o0A8KQC2IM8=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=mqFsSrI0TwvVcxj5zAtCvBlCvLN0If75+VVrQZ8NE0lTwedpsDAMCcBDOoFsI8ddSuKpnXChf4laE4l5kqZA+lkd0vRlKJuuJcoGdvtigxT9SljtZoPNFCd2FrA+EeG/rhOhOdIgbdbgG6rVDBDrqnw06d+qiilqqcGOObjz6aI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=LjCNbVuP; arc=none smtp.client-ip=209.85.222.180 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="LjCNbVuP" Received: by mail-qk1-f180.google.com with SMTP id af79cd13be357-92e5b048375so18418385a.1 for ; Thu, 09 Jul 2026 19:31:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1783650707; x=1784255507; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to:content-type; bh=RkQ/1bstQnfaorhe+sz7JlhppZT7UEc9rxWGwXZ/Tpk=; b=LjCNbVuPjiXQke3mtFvy4TMIbYZgebAqzUvCQ0lGh66lLV7NXvdew2XEqsyIHg14zk qBPgwMUSOIPH6GHXqMczzaD+RznCRWrt2fsnkDgNrYma8T7pqzta0dYg4Ku7hLX1TeaE 9dwiVY4ujKeRdHDLndPLL/mBO2pjGM6cAV4BSo2Ffkp5nq4VzTG+c35ueZAFtrBHq3UK guTtmgcW7ntPuRc84RyNtjxPY5ilu91cwclTE5pzS04819cjToYt/GZX0ymHJjJEaIBC 7io/NBd9pImKdHVUooZUqpWU6lZ4DW/wflP9zpka7gRJj90G/qGPQna/fkKXOyC+pZZx kCyw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1783650707; x=1784255507; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=RkQ/1bstQnfaorhe+sz7JlhppZT7UEc9rxWGwXZ/Tpk=; b=HFT8NxtJKozIkbASCztKd98Jxzj3i95Tj4HASKb17itHXeyTW3SK9nSLwEBFBXOvev lKAAm+FXGtLt5FUyoJrwD531LZq+iYXrOAQ5EGlTvUcN0/Qt2UnB8ElH/7XGmG8MezxH pb+LnrH9W9dy5v99Xk7pU0KwSdywDXS6Yr2ZtEkprQrBd+7qxI3RRYQin+zonfZJyHf7 4nPs8Xqp8ef3kN+M6tL+i9mmOdNuXxqCIt10n7Sp9jJTOM6VO4yGlVnRNZoAP5zqjBHj b+1PA2B14tRqoxTGDRMSAEIZ64IlDgFZWrWcOFWHvW4Ikn+vxHS0S1Q7EYUiIjb2J7IJ +pfA== X-Gm-Message-State: AOJu0YyVhdGw3yGVPMCUJ4GYMuT0VHo8DIb7OMvhu3T7kk0RwCXm8aid cfOKyZi9mtX5l2sCW0EyXdCwCdWh8+AMl/493++pfJ9DRAzTjdV/raHIAOeNCLE8SAc= X-Gm-Gg: AfdE7cljnUYupidhk+5yAufH4a5hIYEKX+f1QzT+PMECN75/lYvb8lc/8y+ogGJuMca /bTKhe1aW5DWVCttLq1uok8Pw2xe6HLATcvIFbmLP6nzQsXbFJAi5MuTJBqkvSX9jcqez3TrDl9 gCX5jzwOUU1HEOXg2IFvnkVihiWIuBiUs0JnrEO1njOoYFDIXKGkHEy15NT1roGanB8A2mD4vKK JBGgJsSaN+miukTwt9DR3q9qDKVAdc0icsJvM2zIUFyxHmt+jtFzOOsEJrgWioDF05NBaPGmz1/ 47ERX78a9lUoksI/U3RfmeszRDJxTgHZN4ih74FupSRzJplke1rGpaxJ3MrvNyzduJLzhd/y2Rf 4WeRajvWJ606/NtyxufvaY0DGedmVQT+TCaQxDaaTmH3d05M4QV2YAnyfUEVK2tTwsAgqmhSjly n6cGV3yqXf5fpkAqmTaCZ0akdyzTst2GlZsC4+mZqBew7tiG4EdPpoHUl62b0gdxjggwkZCMTMZ rwRUT7dLsFeheYbaarWUrMiGlHux8Aai5LJEdF6/1s= X-Received: by 2002:a05:620a:4614:b0:92b:67e6:4b6b with SMTP id af79cd13be357-92ecf6114e1mr1024252085a.66.1783650706639; Thu, 09 Jul 2026 19:31:46 -0700 (PDT) Received: from server0.tail6e7dd.ts.net (c-68-48-65-54.hsd1.mi.comcast.net. [68.48.65.54]) by smtp.gmail.com with ESMTPSA id af79cd13be357-92ee5d5fc4dsm89983185a.40.2026.07.09.19.31.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Jul 2026 19:31:45 -0700 (PDT) From: Michael Bommarito To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org Subject: Please consider 83f99de1b7c0 ("ext2: fix race between setxattr and write back") for 5.10.y, 5.15.y, and 6.1.y Date: Thu, 9 Jul 2026 22:31:42 -0400 Message-ID: <20260710023142.3748810-1-michael.bommarito@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Please consider the following already-mainlined fix for the stable series listed below. Upstream commit: 83f99de1b7c0dcfa42b211e5e40334b7ad786b36 Subject: ext2: fix race between setxattr and write back This is a stable option-2 request for an already-mainlined fix. The patch fixes a security-relevant bug pattern that remains present in the listed stable branches in my current review. Why this belongs in stable: ext2_xattr_set2 allocates a block via the reservation window concurrently with writeback (ext2_get_blocks), tripping rsv_window_dump BUG() in ext2_try_to_allocate_with_rsv (panic/DoS); fix absent in the checked stable branches and the unguarded reservation path plus reservation-using xattr allocation are still present there. Requested stable series: - 5.10.y - 5.15.y - 6.1.y Fresh stable check (2026-07-08): - 5.10.y: 738ac465e4e9 fix shape: absent; upstream diff: needs-adjustment - 5.15.y: c86c4726e7f0 fix shape: absent; upstream diff: needs-adjustment - 6.1.y: 090666d3cc90 fix shape: absent; upstream diff: needs-adjustment - 6.6.y and newer checked longterms already have the fixed shape The source-shape check looked for both the EXT2_ALLOC_NORESERVE xattr allocation call and the matching reservation guard in fs/ext2/balloc.c. Those are absent in the requested branches and present in the checked 6.6.y, 6.12.y, and 6.18.y branches. Backport note: The mechanical check above reports whether the upstream diff applies to each listed branch as-is. Branches marked needs-adjustment may need an equivalent stable backport rather than a straight cherry-pick. The current upstream diff fails in fs/ext2/xattr.c at the same hunk on 5.10.y, 5.15.y, and 6.1.y, so an adjusted backport is expected for all three requested series. Impact: a local user with write access to an already-mounted writable ext2 filesystem with user xattrs enabled can trigger a kernel BUG/oops through user.* xattr churn and writeback pressure. I do not have evidence for privilege escalation, code execution, or confidentiality/integrity impact; this is an availability issue. My current CVSS 3.1 estimate for that mounted-ext2 scope is 5.5. Direct-tracking exposure in my current review includes Debian 11, Debian 12, Amazon Linux 2023, and Android 13/14/15 GKI. Vendor trees that do not directly track the above stable branches need separate per-tree checks. Primary touched files: fs/ext2/balloc.c, fs/ext2/xattr.c No reproducer is included in this public stable request. I can provide additional details privately if needed.