From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 0CCE84F7981 for ; Fri, 4 Sep 2026 17:13:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788542000; cv=none; b=XZ5AG4/GY931hSHzAT34pClltH9YrwrJGHaad4zqzhB1TVKG03HO8VCs1bdg8KFNKuYKuz+bR0jgMiKvcwYN3ZbRuxhQmFBLxGPRoHMs5d29UBR0jTyE+xO8TfQqt88W+czs7WrkFXotlaW1IgprnBQ3U7fE0/UOkWuTFHeBXZk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788542000; c=relaxed/simple; bh=dn+ws0+1xRwfpZ4IjlkAIIIdG9T+i+dOy/ei39bxQSY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=lSMdhaaWK7QPoW+SkSn+UKfj0fAcWtMxVuvfmWOVbdvvxNg1fD/VqT9+XTdrv0+5VxxYctqJJx4NTzPyH8AuCxUGPYuyOi51X4VhwgHZ5q4cH4GtU/Ldt8k9Szlu3NDBVwYD+exYYi2pwXPLhvC5CaeRVw7L5kZbD8mnmIn3DB4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=DuEaE8UL; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="DuEaE8UL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E662F1F00A3D; Fri, 4 Sep 2026 17:13:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788541998; bh=kBQne7t3HVRSfvaHM0uOnZM3cfGWsFFbramwWC9Hp6Q=; h=From:To:Cc:Subject:Date:Reply-To; b=DuEaE8ULW/gPfZEIqo/vTq7QSBcIVxwPQ66yM3iHvK7mNKqxZIR2D98w36fFbNL7I /2gwkRKwGK+eolmP2azg6wMWobF8NBO9mQtDnNHL3mEc3lLF3FWt7J8FteA4MQBeuM XjSmRzqxhnoVf7uY8N1O2r2BYBtLwHxX0CakTDSI= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-80899: erofs: remove fscache backend entirely Date: Fri, 4 Sep 2026 19:09:40 +0200 Message-ID: <2026090431-CVE-2026-80899-c2db@gregkh> X-Mailer: git-send-email 2.55.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3136; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=Iz+3YQbwyLIU5lbZ/OwkMa0BNU9Rvu74Bi9nb1xPABA=; b=owGbwMvMwCRo6H6F97bub03G02pJDFmzfnvfufVUKuf47sC3arsD4r4dELqlHfD5ztxHR69EC 9a+lz/l3RHLwiDIxCArpsjyZRvP0f0VhxS9DG1Pw8xhZQIZwsDFKQATmXqCYcGWa36FwY2Slb1P a8/w//J81vH/ITPDPIPrDrvVROLiV0zjb3esla5JEOQoAAA= X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: erofs: remove fscache backend entirely EROFS over fscache was introduced to provide image lazy pulling functionality. After the feature landed, the fscache subsystem made netfs a new hard dependency, which is unexpected for a local filesystem and has an kernel-defined caching hierarchy which could be inflexible compared to the fanotify pre-content hooks. Therefore, this feature has been deprecated for almost two years. As EROFS file-backed mounts and fanotify pre-content hooks both upstream for a while and already providing equivalent functionality (erofs-utils has supported fanotify pre-content hooks), let's remove the fscache backend now. The main application of this feature is Nydus [1], and they plan to move to use fanotify pre-content hooks in the near future too. I hope this patch can be merged into Linux 7.2, which is also motivated by newly found implementation issues [2][3] that are not worth investigating given the deprecation and limited development resources. The associated fscache/cachefiles cleanup patch will follow separately through the vfs tree (netfs) later: it seems fine since the codebase is isolated by CONFIG_CACHEFILES_ONDEMAND. [1] https://github.com/dragonflyoss/nydus/blob/v2.1.0/docs/nydus-fscache.md [2] https://github.com/dragonflyoss/nydus/pull/1824 [3] https://lore.kernel.org/r/20260619135800.1594811-1-michael.bommarito@gmail.com The Linux kernel CVE team has assigned CVE-2026-80899 to this issue. Affected and fixed versions =========================== Fixed in 7.1.8 with commit f6145794f17a27d25f8a84edb80731fb0e07c196 Fixed in 7.2 with commit c37460cd9b2fcb61ec66b7eb4fde737e65ec2a56 Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2026-80899 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: Documentation/filesystems/erofs.rst fs/erofs/Kconfig fs/erofs/Makefile fs/erofs/data.c fs/erofs/fscache.c fs/erofs/inode.c fs/erofs/internal.h fs/erofs/ishare.c fs/erofs/super.c fs/erofs/zdata.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/f6145794f17a27d25f8a84edb80731fb0e07c196 https://git.kernel.org/stable/c/c37460cd9b2fcb61ec66b7eb4fde737e65ec2a56