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=1793828869; b=whcg0p+PR2opkDYaqZc+vDfCfSRqexpWuCStfsdIlfYPkAJt+ZpvIesQrZMaj8q6msFD kMJnm9dsWL6ImzE8fqvyLAAJrusL+voDAE8c/a0QEw1Stp1dKcxHxLQU92Orviq6B12xc uKE/SH85FV682R3Mv73rFio0482X8EeGHFJQm9KdVNnKLm1cIkksKgULH3Ctx/4zHpoHf hB7C+cit6TL6Lbknw3OIJrepcdyk3XgyYR8iL8Bcw2o6nQLnXyEqKxFrXnRMHTKN0gy3U e5HqheXyfHC/nKUbpjue9vPA77U82QUx8sYAeUqYoq9HZrIXZF/njHzKXJrjyaiCvug== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793828869; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=RICI02i4HTJ8+uE0oLjcANzh4K5cChoEKslvZJVFyM4=; b=mfZeB5kcJ3azhQAYljlwCvAvfVNM2JX7Qq1pe5kxJ/PYIUcU+PaO06yYE6KqIMvTWvEQ nWsDKaon3Gb7fRZiCLAF8qJ+Gkw13jKziR8XHgPnB87e1auIUr7xEQpDgkOdIKxPxI/dY 3IZnAUGkZlwRhqHhAvNmwBsDAfIRym3yAq7hdlkJsQ3HkqQUlyaFPhfmzE4t5duPv2tVx mGqDViaE4z8GvwhEBu3Tp90VYKHCsOr/es4evYiTcAR7W6Z1PIaAkNgn4mHQRj0rN2Xbk L0iYNsDeqHCUi3EBDMCREoB/54y9m6e2dQtszeOfbTmPm4dW2YekZ7SymKkzFB2rBaQ== 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=VL+hXr22; 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 5F61B6070400; Wed, 4 Nov 2026 21:47:49 +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=VL+hXr22 Received: by smtp.kernel.org (Postfix) with ESMTPSA id EFE8B1F00919; Wed, 4 Nov 2026 21:47:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793828869; bh=RICI02i4HTJ8+uE0oLjcANzh4K5cChoEKslvZJVFyM4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=VL+hXr22slPtc3kcqDYxss46/z6PV0+y38e/oGcsFdkA20GQqmABE6MQixNclB5Dk UnYGRRgYuDpTjLECiaGt+c+VWZDv6dnsFp88EJwxJ7YCcceMo156xzQ+S9tWAN0MiS D4SN1/u/W7/r5a7D8C4PWeTXBNfb6OGtwKch4e+c= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Chris Mason , Josef Bacik , Amir Goldstein Subject: [PATCH 7.3 291/547] ovl: fix a torn path in ovl_get_redirect() Date: Wed, 4 Nov 2026 16:07:55 -0500 Message-ID: <20261104211046.471568214@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211038.406938024@linuxfoundation.org> References: <20261104211038.406938024@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chris Mason commit 2001cd7ca5560198131e46c6ca3c3472b06145c2 upstream. A hard link of a metacopy file that races with a rename of an ancestor stores a redirect to the wrong lower file. Each component of an absolute redirect must be the name that a dentry has in the parent that the walk continues with. ovl_get_redirect() copies the name under d_lock and calls dget_parent() after the unlock, and the callers for a hard link hold no lock that stops a rename across directories. A rename between the two steps combines the old name with the new parent. With delays in ovl_get_redirect(), an unprivileged user hard-linked a metacopy file while renaming its ancestor to another directory, the stored redirect named another lower path, and after a remount the file showed the data of a root-only file. Fix this by taking the parent first and checking it again under d_lock. Fixes: e04527fefba6 ("ovl: fix dentry leak in ovl_get_redirect") Cc: stable@vger.kernel.org Signed-off-by: Chris Mason Signed-off-by: Josef Bacik Signed-off-by: Amir Goldstein Signed-off-by: Greg Kroah-Hartman --- fs/overlayfs/dir.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -1027,7 +1027,19 @@ static char *ovl_get_redirect(struct den const char *name; int thislen; + /* + * A rename can move d to another directory at any time. Hold + * d_lock to copy the name that d has in this very parent, or + * else the path mixes the old name with the new parent. + */ + tmp = dget_parent(d); spin_lock(&d->d_lock); + if (unlikely(tmp != d->d_parent)) { + spin_unlock(&d->d_lock); + dput(tmp); + continue; + } + name = ovl_dentry_get_redirect(d); if (name) { thislen = strlen(name); @@ -1040,13 +1052,13 @@ static char *ovl_get_redirect(struct den if (thislen + (name[0] != '/') > buflen) { ret = ERR_PTR(-EXDEV); spin_unlock(&d->d_lock); + dput(tmp); goto out_put; } buflen -= thislen; memcpy(&buf[buflen], name, thislen); spin_unlock(&d->d_lock); - tmp = dget_parent(d); dput(d); d = tmp;