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 5ECCA3F5BD7 for ; Thu, 3 Sep 2026 09:56:24 +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=1788429386; cv=none; b=mhGj5wWJ/NeypvHNRv2w6RSarG9NBokWzrq3EsjmLMfA1r29dezlCplcSfQ+NI2sYpPvnLxyqkYqyAifRbvvc8KXM/pxuZDR850bUmY1Hf1hdNxVoxrdObp516SG1sghgQp/+qx9dCp4+DjUfbVTng1EJu9poloxi1imdyVJcOg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788429386; c=relaxed/simple; bh=hRuOLgXhB+WPMRAUf5/DJP08uvCSXwvBRuLFldgBs5I=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=OAsoJIsiHf5RnVfU2/0o7x0E53U6GCxRrLf7AvWuF0pSDjSymXajHnTb5/CxVrNQMKkgRaB/Md5RQBaz3/OTRlkdrQLpaBH71diS5voJi/yDhKerBMSvQSdFfSvVrXxRFYX+tpTGgy5aNGQGBO2kA6z3D2FbsmILLOlYBgiO+zY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=zsIzQFCn; 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="zsIzQFCn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5731F1F000E9; Thu, 3 Sep 2026 09:56:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788429384; bh=5KAjGdcFdapfg0Es6RRAB87zUjDrH5uwavE4g612KT8=; h=Subject:To:Cc:From:Date; b=zsIzQFCnweMxCDHtQL7PRtB3SX+0xUl8G3NaE8mt+5Qy9JBoZ2jLSeXt/rCNcuFPW v1Jug1f7avqCBUsGh3325TB+pVfSO77ZNz1cDZfYjPLSEABL6VLb1+zJ/1DGrJQdzc QU0t21hkXBN5pm/2B2pYw9Vloe0V8sr5KztMCR68= Subject: FAILED: patch "[PATCH] ovl: fix double end_creating() on the casefold-mismatch path" failed to apply to 6.18-stable tree To: vivek.parikh@breachx.ai,amir73il@gmail.com,brauner@kernel.org Cc: From: Date: Thu, 03 Sep 2026 11:56:19 +0200 Message-ID: <2026090319-clanking-sandstone-d89f@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 6.18-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-6.18.y git checkout FETCH_HEAD git cherry-pick -x 077ab8985ee278c3d8618182d335b0f0cd919e16 # git commit -s git send-email --to '' --in-reply-to '2026090319-clanking-sandstone-d89f@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 077ab8985ee278c3d8618182d335b0f0cd919e16 Mon Sep 17 00:00:00 2001 From: Vivek Parikh Date: Wed, 5 Aug 2026 10:27:54 +0530 Subject: [PATCH] ovl: fix double end_creating() on the casefold-mismatch path ovl_create_real() releases the new dentry twice when the casefold consistency check fails. The S_IFDIR branch calls end_creating() and sets err, then falls through to the common out: label which calls end_creating() on the same dentry again: case S_IFDIR: newdentry = ovl_do_mkdir(ofs, dir, newdentry, attr->mode); err = PTR_ERR_OR_ZERO(newdentry); if (!err && ofs->casefold != ovl_dentry_casefolded(newdentry)) { pr_warn_ratelimited(...); end_creating(newdentry); /* first */ err = -EINVAL; } break; ... if (err) goto out; ... out: if (err) { end_creating(newdentry); /* second, same dentry */ return ERR_PTR(err); } end_creating() is end_dirop(), which does inode_unlock() on the parent and dput() on the dentry, so the parent directory's i_rwsem is unlocked twice and the dentry is put twice. The second unlock releases a lock that is not held, which is what wedges every later creation under that parent, and the second dput() drops a reference that was never taken. The branch was added by commit dfc7da402ccc ("ovl: Check for casefold consistency when creating new dentries") as a bare dput(), which already released the reference twice; commit fe497f0759e0 ("VFS: change vfs_mkdir() to unlock on failure.") converted both sites to end_creating(), adding the double unlock. This is reachable by an unprivileged user. The casefold consistency of the layers is validated at mount time in ovl_parse_layer(), and again on every lookup in ovl_lookup_single(), but ofs->workdir is the internal "work" subdirectory created inside the user-supplied workdir, and that subdirectory is not re-checked. Marking it casefolded after the mount therefore makes every ovl_create_temp() inherit the wrong state - and that path reaches ovl_create_real() through ovl_start_creating_temp(), which uses start_creating() with a generated name and so never runs the lookup-time check. unshare -Urm mount -t tmpfs -o casefold=utf8-12.1.0 tmpfs mnt mkdir -p mnt/lower/d mnt/upper mnt/work mnt/merged mount -t overlay ovl -o lowerdir=mnt/lower,\ upperdir=mnt/upper,workdir=mnt/work mnt/merged chattr +F mnt/work/work mkdir mnt/merged/d/sub # directory copy-up overlayfs: wrong inherited casefold (work/#5) and the next copy-up blocks forever on the parent's i_rwsem: mkdir D start_creating+0x65/0xb0 ovl_start_creating_temp+0xb0/0xe0 [overlay] ovl_create_temp+0xa3/0x1d0 [overlay] ovl_copy_up_one+0x1f1c/0x21c0 [overlay] ovl_copy_up_flags+0xf5/0x140 [overlay] ovl_create_object+0xb7/0x220 [overlay] ovl_mkdir+0x23/0x40 [overlay] Drop the end_creating() from the branch and let out: own the cleanup, which is what every other error path in this function already does. Fixes: dfc7da402ccc ("ovl: Check for casefold consistency when creating new dentries") Cc: stable@vger.kernel.org Signed-off-by: Vivek Parikh Reviewed-by: Amir Goldstein Signed-off-by: Christian Brauner (Amutable) diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index a7a393b04277..3cd8194cbb1d 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -188,7 +188,6 @@ struct dentry *ovl_create_real(struct ovl_fs *ofs, struct dentry *parent, if (!err && ofs->casefold != ovl_dentry_casefolded(newdentry)) { pr_warn_ratelimited("wrong inherited casefold (%pd2)\n", newdentry); - end_creating(newdentry); err = -EINVAL; } break;