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 5364E3382CB; Sat, 12 Sep 2026 13:30:18 +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=1789219819; cv=none; b=rA/FU+d6Gv+sm5CBKmlBJL+A7iddNSNrTQvHfpowTBLJOggy8QnHpvsnzM5XjGcouzweB13g2ZE7JKL8ki6l6UV/ITDdmGMt9Gx3TCnEM7/DY4ffNQQvjfjDCdKyWxPEZhEKwpa0g6nK7D3voQ/QkQBiCL6dbZTsrqzszTJizWI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789219819; c=relaxed/simple; bh=A40qLgCzV0vOTaFih1nJMcVV+kVPQYmFoNsZ0yEaInE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Wo94oDt/uv+KAF6k9VvSkhmdKIbyg/G72ynVyhPWr+iWqLWyXr+ScwlTJQ3A32NzcuDv3UERvRmTWlRKUvpWf6W6iMF40QWWfd+/j16I8BNr5Bwh+8W4zxYFa/JcPvgsojV68ROyHm7r1JzCxAj4BF/d+CU7Yu6rKL0GnC5CIyA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=xhjA2Ds6; 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="xhjA2Ds6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CF13C1F000FF; Sat, 12 Sep 2026 13:30:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789219817; bh=GWtyMg4Ioy0JPH+USx+1GPm0j/A7rtf4ZnZcai7kAJI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=xhjA2Ds6fyZ9IgZRKtHR1VkQXcgmQ/dvjSBGD8bKZ8MTQQ/uogqT7igtY+jJxV9Hj Vxxd9Lzdgk7n262phTOs9VrcOQJC0NmWsS8N3rrT1hKjTYFe8CGhJ/CJEe3ekeUItU CFXQhriMcgpGJAg+LxoTqQmtoRs3hNQe9bBuEoHM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Chris Mason , Chuck Lever Subject: [PATCH 6.6 0051/1424] nfsd: release path refs on follow_down() error Date: Sat, 12 Sep 2026 08:41:23 +0200 Message-ID: <20260912065608.445768683@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065607.279695368@linuxfoundation.org> References: <20260912065607.279695368@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chris Mason commit 6cba08dc1922140d260cfeb30bbda4ee1bf869d8 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- fs/nfsd/vfs.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -134,8 +134,10 @@ nfsd_cross_mnt(struct svc_rqst *rqstp, s 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 */