From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793802916; b=mvQiyTb/htDw3kkjeiaw7lYhsJJGhBr1lSAEyk4lVgXhKxfJEU9gSaprS4IrqqO2o+2l gnPfFshcgPydbxQu7RnNvvN0BUbr/wtyIj/3Y+p9u0JDzPjJKWIPia5CxBpJ7Lj+tMbsF I+3AzFXXaoJTpGtotHTzvEBgCePeg4lYptJcGwI6OYtUMKTRKQMp2jXlsEFmzOtY/9dvc QqifaUkg4y8/ad3fiFA8ih0nFS/NC2roFq8PxYqUtNm2S1iHcYp81jU1QDzHpdBBy85d+ Y3ZFYWuLMZOCL9UAjG7Mzpwz1UyIiYRGpz0sYP5mw5waQLaMfwpM4xIUByEtlHnnvig== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793802916; h=Received:DKIM-Signature:Subject:To:Cc:From:Date:Message-ID: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=ZJzRPIIoYzHeh/hFcxgjVYlQ4Zr3AOy8SynW9BTCo6g=; b=kX0nmKroi16kSlT9Y7YtdVLPVKoBk2/Q39VIZ6dZmK8dS6EMrUwGUJieNBVgT2aPQ3it MGtA4QRV6be1M0VBSi2CVSPAFbY8Wmklo8uKHuBoI0UezapZocwJTMwywR4ECScAuf+3Q UE5ZJXN3uzd595YFY7bZGhD2QmmLJdAh64ZaedZdP+AablBoygSWMDvzRq4r2olrblEou ci18RzsAkSOxKgQeCou+oIM3fJUOvemmY2awbHrLJBNbdskHiT1NarT1gsBY8YAo5UyMV Q9vvZkdJ329dBCcYnsvzqLgs5zsRcyjXId77pwfdtq/5+j6V4fwv/gWkOjynOvzQ6lg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=RZL13BM+; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 08ACC606A326 for ; Wed, 4 Nov 2026 14:35:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=RZL13BM+ Received: by smtp.kernel.org (Postfix) with ESMTPSA id AAD7D1F000C1; Wed, 4 Nov 2026 14:35:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793802915; bh=ZJzRPIIoYzHeh/hFcxgjVYlQ4Zr3AOy8SynW9BTCo6g=; h=Subject:To:Cc:From:Date; b=RZL13BM+61KYcvOJ+PczaHZgmxfHAunTGpfeP0LEfECrje96cyYc38MMg49C9Gq4g qIkpkvBvQ++m0sZav3y/7/m4q7izz4UMjqecnWT1JKp/1QCqmmIH3Qxr+xsnAMZ9cu VdN7DF4uCWYnxxMHxZlcyAmRAwcvcXJV+USMbDWM= Subject: FAILED: patch "[PATCH] ovl: take a snapshot of the name for copy up" failed to apply to 6.6-stable tree To: mason@kernel.org,amir73il@gmail.com,josef@toxicpanda.com Cc: From: Date: Wed, 04 Nov 2026 15:35:14 +0100 Message-ID: <2026110414-plexiglas-angelfish-3128@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list 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 6.6-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-6.6.y git checkout FETCH_HEAD git cherry-pick -x 65bf000962a33ec9d2488e4e1797b6cf630abcbb # git commit -s git send-email --to '' --in-reply-to '2026110414-plexiglas-angelfish-3128@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 65bf000962a33ec9d2488e4e1797b6cf630abcbb Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Wed, 7 Oct 2026 10:34:08 +0000 Subject: [PATCH] ovl: take a snapshot of the name for copy up The copy up of a directory reads a freed dentry name when a lookup moves the directory at the same time. A pointer to the name of a dentry is only valid while something stops a move of the dentry. ovl_do_copy_up() keeps a plain copy of c->dentry->d_name in c->destname, and ovl_copy_up_start() only keeps ovl_rename() away. When a lookup finds the same directory under another name after a change to the lower layer, d_splice_alias() moves the dentry and frees its external name. With a delay in ovl_do_copy_up(), a chmod of a lower-only directory with a 60 byte name raced with a rename of that directory in the lower layer and a stat of the new name, and KASAN reported a use-after-free in lookup_noperm_common(). Fix this by using take_dentry_name_snapshot() for c->destname. Fixes: 829c28be9bb9 ("ovl: use d_splice_alias() in place of d_add() in lookup") Cc: stable@vger.kernel.org Signed-off-by: Chris Mason Signed-off-by: Josef Bacik Signed-off-by: Amir Goldstein diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index 92b3d08a0234..12000e45fefc 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -920,6 +920,7 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c) struct ovl_fs *ofs = OVL_FS(c->dentry->d_sb); struct dentry *origin = c->lowerpath.dentry; struct ovl_fh *fh = NULL; + struct name_snapshot name; bool to_index = false; /* @@ -957,12 +958,15 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c) goto out_free_fh; } else { /* - * c->dentry->d_name is stabilzed by ovl_copy_up_start(), - * because if we got here, it means that c->dentry has no upper - * alias and changing ->d_name means going through ovl_rename() - * that will call ovl_copy_up() on source and target dentry. + * ovl_copy_up_start() keeps ovl_rename() away from c->dentry, + * because ovl_rename() calls ovl_copy_up() on source and target + * dentry. It does not stop d_splice_alias() from moving a + * directory that a lookup found under another name after a + * change to the lower layer. That move frees an external name, + * so take a snapshot. */ - c->destname = c->dentry->d_name; + take_dentry_name_snapshot(&name, c->dentry); + c->destname = name.name; /* * Mark parent "impure" because it may now contain non-pure * upper @@ -971,7 +975,7 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c) err = ovl_set_impure(c->parent, c->destdir); ovl_end_write(c->dentry); if (err) - goto out_free_fh; + goto out; } /* Should we copyup with O_TMPFILE or with workdir? */ @@ -1005,6 +1009,8 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c) out: if (to_index) kfree(c->destname.name); + else + release_dentry_name_snapshot(&name); out_free_fh: kfree(fh); return err;