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 4C8E24AA401 for ; Thu, 3 Sep 2026 13:18:10 +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=1788441500; cv=none; b=b8m9r+aISJKFHJhIYuPR21KA+cFOvg6WgzdRgN4P1ADYcr4+vv4GZq5xLEAAMfPcFrsPDDdq7w4roT0p0eKbuM0vF2TZjmFF7iDolU+BRTgI75XFN5I1Pce6nlGdZ3WMrR2HAN6PDB578941e5BwBSGCFQ5Ivs2uggQ7JQn/cIM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788441500; c=relaxed/simple; bh=zgKR1OMUk/omF3oV2IErJKN7olu5+bsjtcryQ5lvpVM=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=Jjy9VaTIP6vGgtCPK3dHJWezwcI6aZ178q7vlqIAxKdUXa6dutTKLHCE48RkJUHcZmE3UVKJnARY7bgsnSdTMcKGH3YxE04AqBWUao282KyXkgfVk2MyUN4eCgazDAouFVr3iH7wn649hHwooAfQbCBjUrY161S1fjVFgopD1vs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ZlLlhLUw; 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="ZlLlhLUw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B52121F00A3A; Thu, 3 Sep 2026 13:18:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788441489; bh=b11nXBiQjY6mvCh3n/dUfZTSAY//JjSqQA/qW6SwTgU=; h=Subject:To:Cc:From:Date; b=ZlLlhLUwZTC8YIXP60GTD9EbXeoQzp9A0UuqRUdBtZBKVoADiQcuFMeqDIsj2sRHb Jfs908j6IhbS7Y9WJJ0l8kypECaGXwY+QdFHNx4IIx5UKr0uxVDn2zqFXkVM3J1/R7 cRglFTH6Yq70JGN837LvXDAa6KHXDJGvFZZ2gIO0= Subject: FAILED: patch "[PATCH] nfsd: release path refs on follow_down() error" failed to apply to 5.15-stable tree To: clm@meta.com,chuck.lever@oracle.com Cc: From: Date: Thu, 03 Sep 2026 15:07:24 +0200 Message-ID: <2026090324-reprogram-throwaway-926d@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 6cba08dc1922140d260cfeb30bbda4ee1bf869d8 # git commit -s git send-email --to '' --in-reply-to '2026090324-reprogram-throwaway-926d@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 6cba08dc1922140d260cfeb30bbda4ee1bf869d8 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Sun, 31 May 2026 08:06:59 -0400 Subject: [PATCH] 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. Fixes: cc53ce53c869 ("Add a dentry op to allow processes to be held during pathwalk transit") Cc: stable@vger.kernel.org Assisted-by: kres:claude-opus-4-7 Signed-off-by: Chris Mason Link: https://patch.msgid.link/20260531-nfsd-testing-v1-2-7bfa481b0540@kernel.org Signed-off-by: Chuck Lever diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 0dcfaab95021..f73012bc742f 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -137,8 +137,10 @@ nfsd_cross_mnt(struct svc_rqst *rqstp, struct dentry **dpp, follow_flags = LOOKUP_AUTOMOUNT; err = follow_down(&path, follow_flags); - if (err < 0) + if (err < 0) { + path_put(&path); goto out; + } if (path.mnt == exp->ex_path.mnt && path.dentry == dentry && nfsd_mountpoint(dentry, exp) == 2) { /* This is only a mountpoint in some other namespace */