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=1793829707; b=XGWzSll0M8pHikzHKErtIdze7ZxNHGFuMIlciap0ms9+triy+RSaD21zV7Os47D9z+BP 8tmJcoPRX47g3xOYT/2Y2jcp6KcbaSPk/OL9D6xekkcrFGF/Bdk0g0o3LNS+8pNYicaOd soUQZOiv+c+x5XUjIoH7CS/D56X6SevT0UOK4cttAfXwGf0sOmt6ndc4H9NrFxOVL8oyV aVi2pUr2Zh8nOcPNWxUQgwA7tjX3JniDh5vFO/WueH5KGoUstJMltRBhFDyLrRnn4qHbg xWTnShuF0bG6OyXghojK5ZC6wxoG0zPh16SC7L/d9+ospIRvsJOJbVluj9SiJm+ltZQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793829707; 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-Type:Content-Transfer-Encoding; bh=j5uuaQvE58Oz+Q1Mgq27pBsRJ4rkWkbwR8fWPMtuiR4=; b=QWYP9bdsbRnL9DY7MD582NVgGve4IDqObzOY5C9zQAlhH0y2S5JHx5ChEmFPktYgLLbB GRov7evYys9yz3Z7sRivOYsjKveA1mdMif6JQFOwZ9QQt/7nM+Ct9Zkmp9u2xenng4yCw ydE1Sek16TIN3hBHYh31tRZFbs0hYfq1PPMqeMPOt9u+EB1Fl5h/M/XXx4JVrqan2V4c+ 1UtrfzYup6WcBF4evgkoBnqfidge+nk07vw6AW40Er8YBwWfMr2EY7FCf+WQ7LMm223tB 4mKRGjhJF7V/NIwUKdElATySp4P645MIkR6TiQ9Nlhe7SLGXHZ5OYeiuOLGMKEqgLZw== 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=MnoDxmWg; 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 B8A0F606BA3C; Wed, 4 Nov 2026 22:01:46 +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=MnoDxmWg Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3420E1F00919; Wed, 4 Nov 2026 22:01:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793829706; bh=j5uuaQvE58Oz+Q1Mgq27pBsRJ4rkWkbwR8fWPMtuiR4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=MnoDxmWgRDq+PRE2j0qeVopQ+L0b2evuJ4cWYOk7962M0rbG5tnw4tUp+y3Mmj6pa 3j9FB/wblCR2KXvpbgMYBQ5B8vJu3hVNtLQCaBGwRB5hR4yxCk2JrCtCZ3A8jvYAzu Lac/XAh1LDCNa2t4SsWNpYFTtugFBiyQ5kKPSSXo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?=EC=9D=B4=EC=83=81=ED=98=B8?= , "Christian Brauner (Amutable)" , Sasha Levin Subject: [PATCH 6.18 0291/1005] romfs: detect hard link cycles Date: Wed, 4 Nov 2026 16:00:24 -0500 Message-ID: <20261104211052.062603044@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211043.516122098@linuxfoundation.org> References: <20261104211043.516122098@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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: 이상호 [ Upstream commit d30b5a954e0a4dcc16bba9c310c13709a6169a52 ] romfs_iget() follows on-disk hard link entries until it reaches a non-hard link inode: pos = be32_to_cpu(ri.spec) & ROMFH_MASK; The target position is image-controlled, and the loop does not detect cycles. A crafted romfs image can make the root inode a hard link. The hard link can point back to itself and leave mount(2) spinning in the kernel. Reject excessive hard link indirection with -ELOOP. Normal romfs images do not need long hard link chains. This bounds corrupted-image traversal. Propagate romfs_iget() errors from lookup because hard link traversal can now fail with -ELOOP. Signed-off-by: 이상호 Link: https://patch.msgid.link/20260701220729.822112-1-kudo3228@gmail.com Signed-off-by: Christian Brauner (Amutable) Signed-off-by: Sasha Levin --- fs/romfs/super.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/fs/romfs/super.c b/fs/romfs/super.c index e83f9b78d7a16..9b997831a46bc 100644 --- a/fs/romfs/super.c +++ b/fs/romfs/super.c @@ -240,6 +240,8 @@ static struct dentry *romfs_lookup(struct inode *dir, struct dentry *dentry, if ((be32_to_cpu(ri.next) & ROMFH_TYPE) == ROMFH_HRD) offset = be32_to_cpu(ri.spec) & ROMFH_MASK; inode = romfs_iget(dir->i_sb, offset); + if (IS_ERR(inode)) + return ERR_CAST(inode); break; } @@ -262,6 +264,8 @@ static const struct inode_operations romfs_dir_inode_operations = { .lookup = romfs_lookup, }; +#define ROMFS_MAX_HARDLINK_DEPTH 64 + /* * get a romfs inode based on its position in the image (which doubles as the * inode number) @@ -273,6 +277,7 @@ static struct inode *romfs_iget(struct super_block *sb, unsigned long pos) struct inode *i; unsigned long nlen; unsigned nextfh; + unsigned int depth = 0; int ret; umode_t mode; @@ -289,6 +294,9 @@ static struct inode *romfs_iget(struct super_block *sb, unsigned long pos) if ((nextfh & ROMFH_TYPE) != ROMFH_HRD) break; + if (++depth > ROMFS_MAX_HARDLINK_DEPTH) + return ERR_PTR(-ELOOP); + pos = be32_to_cpu(ri.spec) & ROMFH_MASK; } -- 2.53.0