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 9C60B58FD29 for ; Fri, 11 Sep 2026 20:05:14 +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=1789157117; cv=none; b=ojgZf4mgc7ZdZApMMfJYHaNeIAa/FWcy/0yqJdeVB+VSfIJ3oW2EhM9dKMEqOK1YotJB6vpiFWNwMY3f8UFGNwxaAy2osFJ20XBpOm3/8k1rJwVnl6Sp4/sTSK0WvEujlcpTftiD6/DGhDVPP1Yb2kPcobaxcHMmnd3H9al+V/o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789157117; c=relaxed/simple; bh=R2rjQo0U0ZioIpm2Ttp/K5m+1hABdCaRyxi3/QjiMl0=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Q5COaA+R1ukMB59LgDF1KteEqiJm9X6Evd9iGmdAqiTfPNzmaJBfl9PYPnw1MP+qGhR8WyGliRIAiQpTZQ57Lsm5s/Bu6YLbWzFk2xsi98qnhubA3Rx+hGkyxI8kgelDFW7+rw6yhDZwuqvAXkMgXcOrPySV6HYbjkRsBQz8pKw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=lfRvqk3B; 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="lfRvqk3B" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E95D21F00898; Fri, 11 Sep 2026 20:05:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789157114; bh=VU0CrtktyoNArW8S0PtousizGbLEiq6I4itGErPdGzM=; h=From:To:Cc:Subject:Date:Reply-To; b=lfRvqk3BQU+Nx+6UynPXQW1m3fOzPhcVPwcAQ6bxE8TGvAZchSwcyZDbp5Diqd+VS segUGFaNaUHZybfiurdcYbAMiXKvFlr4zL+LogYA12jQxsDFvHMcfqMPh65thjMJnV Ay+fOmwWM8RdNK75PgGpgV3WoFwRiC9rnaASwsFQ= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89707: nfsd: release path refs on follow_down() error Date: Fri, 11 Sep 2026 21:46:36 +0200 Message-ID: <2026091157-CVE-2026-89707-aca4@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=3279; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=d2rXp2BODvH5Wid7K/4SCN+LhYVv2IW3cr+X55dLON4=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlLIluPC0VWTFx3dvJyzQo2xR/rHHdK6XbrWO3ZxD7B6 W9aZ9vxjlgWBkEmBlkxRZYv23iO7q84pOhlaHsaZg4rE8gQBi5OAZjIpgyG+V4iTpXnrO6Hnjsf aryo1v/Xg+SJ9gxzxfevnyR8+swCphUryt5sXS7Py9MjCwA= 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: nfsd: release path refs on follow_down() error nfsd_cross_mnt() initializes a local struct path with mntget() and dget() before calling follow_down(). On a negative return the error arm jumps to out without releasing those references: err = follow_down(&path, follow_flags); if (err < 0) goto out; follow_down() never drops the caller's entry-time refs on any error sub-case; for example a pre-cross d_manage() failure leaves path untouched, so the mntget()/dget() taken on entry survive the call. Every other early-exit arm in nfsd_cross_mnt() (other-namespace return, IS_ERR(exp2), and the success tail after the swap) already calls path_put(&path); the err < 0 arm is the lone omission. The leak inflates mnt_count and d_count on each failed cross-mount, blocking umount and pinning dentries against the shrinker, and is reachable by any authenticated NFS client through nfsd_lookup_dentry or the NFSv4 READDIR encode path. Fix by calling path_put(&path) before the goto out in the err < 0 arm so the entry-time refs are released on all follow_down() error returns. The Linux kernel CVE team has assigned CVE-2026-89707 to this issue. Affected and fixed versions =========================== Issue introduced in 2.6.38 with commit cc53ce53c86924bfe98a12ea20b7465038a08792 and fixed in 6.12.109 with commit 194316df81263519156ebe714c4a286bee00e5be Issue introduced in 2.6.38 with commit cc53ce53c86924bfe98a12ea20b7465038a08792 and fixed in 6.18.50 with commit 467d56fd3ff57447a790c6dc3ede2d02a947d224 Issue introduced in 2.6.38 with commit cc53ce53c86924bfe98a12ea20b7465038a08792 and fixed in 7.2.4 with commit 2bc4343308d85ee4e0dd3877b384306c96f114c2 Issue introduced in 2.6.38 with commit cc53ce53c86924bfe98a12ea20b7465038a08792 and fixed in 7.3-rc1 with commit 6cba08dc1922140d260cfeb30bbda4ee1bf869d8 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-2026-89707 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: fs/nfsd/vfs.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/194316df81263519156ebe714c4a286bee00e5be https://git.kernel.org/stable/c/467d56fd3ff57447a790c6dc3ede2d02a947d224 https://git.kernel.org/stable/c/2bc4343308d85ee4e0dd3877b384306c96f114c2 https://git.kernel.org/stable/c/6cba08dc1922140d260cfeb30bbda4ee1bf869d8