From nobody Mon Feb 9 08:53:47 2026 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.13]) (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 CF2151B27D; Thu, 22 Aug 2024 01:25:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.13 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724289937; cv=none; b=cdcMS/coGtSOaz1mQUB+V+6eTpt56oupAfvnOx3yWnPda38h3Hs/9VEatTv2DoQ1khaH0TvXz7GQuI344FOAJGNR6E7LGlbJN35EDRUSCUTzWmKW2n4RX2YmISWvtv8bcYk6x9iyAb2kjVceO1YU0vuQKnwl4P/PawCz8UQSEU4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724289937; c=relaxed/simple; bh=CZkEIxc+FPJaU+fDIa1vfhmaBsh7YXbodcWi0F7voVM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qz0imvXHt/dzY3waWn7fBTphbyOGuhXdbtiIZ+CiseD3VHqXh4NosSt1BncRysLuALal+AQXmYB7bUN+iCh7yvG8Z/Z8cfl79nUAUI2Gf0hVsgN9Gwpx2H3CM3dgfzzUQqqeIb0AjPveTxS2mLDzqWOVvNA2fKm2CgVs8YM7tg8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=FsyfWWA8; arc=none smtp.client-ip=192.198.163.13 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="FsyfWWA8" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1724289936; x=1755825936; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=CZkEIxc+FPJaU+fDIa1vfhmaBsh7YXbodcWi0F7voVM=; b=FsyfWWA8Bxpz6Xc9zKMSMAayNK9t+c3cn9obsKUZqc4sVh+P3c8FA+BE PhSYs+yWfb6aBb0Bdj12bafL0uWGSQ/dbgRnVsujsd/ulqkRLCnBmgpwn o6ALKZQL+pUZ4T8D0DqMG8zbVUlRk6R+eVGL9G6BtClysSMXCgdg1wus2 OzUKMfB98Re3469rYhNG/fO++VSoF6gvuaRgYczE8hHotwSU/OsNoiOR2 Ufk2qg/KsWzNb+0i0nuDfRSiQe77A2blJ23CvQfRUmmaQltED9a+ujGQZ OwAApkd/1yKhCI7bvr8XLCzBNSXTXiOIECecIW8EUoKa1EgCzmwi+TEGU w==; X-CSE-ConnectionGUID: CvimTQMATLKimauT2WpTrA== X-CSE-MsgGUID: Tub3MiOORFGOqff8cOUifg== X-IronPort-AV: E=McAfee;i="6700,10204,11171"; a="25574733" X-IronPort-AV: E=Sophos;i="6.10,165,1719903600"; d="scan'208";a="25574733" Received: from orviesa007.jf.intel.com ([10.64.159.147]) by fmvoesa107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Aug 2024 18:25:32 -0700 X-CSE-ConnectionGUID: qGd1H4ZLS7iaqbvcQt7jbw== X-CSE-MsgGUID: ZvvVH9+UTlSlgf/5Z8ERMg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.10,165,1719903600"; d="scan'208";a="61811028" Received: from unknown (HELO vcostago-mobl3.jf.intel.com) ([10.241.225.92]) by orviesa007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Aug 2024 18:25:32 -0700 From: Vinicius Costa Gomes To: brauner@kernel.org, amir73il@gmail.com, hu1.chen@intel.com Cc: miklos@szeredi.hu, malini.bhandaru@intel.com, tim.c.chen@intel.com, mikko.ylinen@intel.com, lizhen.you@intel.com, linux-unionfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Vinicius Costa Gomes Subject: [PATCH v2 04/16] overlayfs: Document critical override_creds() operations Date: Wed, 21 Aug 2024 18:25:11 -0700 Message-ID: <20240822012523.141846-5-vinicius.gomes@intel.com> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240822012523.141846-1-vinicius.gomes@intel.com> References: <20240822012523.141846-1-vinicius.gomes@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add a comment to these operations that cannot use the _light version of override_creds()/revert_creds(), because during the critical section the struct cred .usage counter might be modified. Signed-off-by: Vinicius Costa Gomes --- fs/overlayfs/copy_up.c | 6 +++++- fs/overlayfs/dir.c | 3 +++ 2 files changed, 8 insertions(+), 1 deletion(-) diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index a5ef2005a2cc..7dec275e08cd 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -718,8 +718,12 @@ static int ovl_prep_cu_creds(struct dentry *dentry, st= ruct ovl_cu_creds *cc) if (err < 0) return err; =20 - if (cc->new) + if (cc->new) { + /* Do not use the _light version, the credentials + * ->usage might be modified. + */ cc->old =3D override_creds(cc->new); + } =20 return 0; } diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index ab65e98a1def..851945904385 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -584,6 +584,7 @@ static int ovl_create_or_link(struct dentry *dentry, st= ruct inode *inode, const struct cred *old_cred; struct dentry *parent =3D dentry->d_parent; =20 + /* Do not use the _light version, cred->usage might be modified */ old_cred =3D ovl_override_creds(dentry->d_sb); =20 /* @@ -1159,6 +1160,7 @@ static int ovl_rename(struct mnt_idmap *idmap, struct= inode *olddir, goto out; } =20 + /* Do not use the _light version, cred->usage might be modified */ old_cred =3D ovl_override_creds(old->d_sb); =20 if (!list_empty(&list)) { @@ -1314,6 +1316,7 @@ static int ovl_create_tmpfile(struct file *file, stru= ct dentry *dentry, int flags =3D file->f_flags | OVL_OPEN_FLAGS; int err; =20 + /* Do not use the _light version, cred->usage might be modified */ old_cred =3D ovl_override_creds(dentry->d_sb); err =3D ovl_setup_cred_for_create(dentry, inode, mode, old_cred); if (err) --=20 2.46.0