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 7CCDA3B0598; Thu, 30 Jul 2026 15:20:17 +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=1785424818; cv=none; b=mKM4ywTOIE4U22UKE0fqTxIAz/YN/awOpRpYtDBfUrfRGN12g9PDQS75npxMH7fyU/w8I+hkmyscXpR2IiV2dUO3SeQkznJXt6Ev6HWerX+7DsW2JZwoTKg7CfMZ3z9VfxRUcE1ix5M3XnctQiHSMemX4zjTLLu0goWfWQCY2hI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785424818; c=relaxed/simple; bh=KqertNnBWKOwR2moQluWVFszRYzGaS0Btes9xYgCuVg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=fQBV4RvrquFnvTQ+TMNKnjjB+fbixF0YtT07L2CQjCBZECRr3XrhR+G6rLM9TEBeCfbPW/JevX9uhHIISAD0zbMm5lG85oK4MUBJ+N7ZHghGWztdMzRFjopmGVEOAkzTZH6dxLOig/JJFKny+FE5iES1apjKwMbGz5sIe28mGv0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=jfn+ed6n; 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="jfn+ed6n" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D7F5A1F000E9; Thu, 30 Jul 2026 15:20:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785424817; bh=Oc/B8cC3u9zXHTS7+MzcBhqG+vGiBXar6+pqjVOCV80=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=jfn+ed6n9OgltSHqhRglHvkcnjJEjE2HQvzVYjNPJRW/JqKe5qyr9bt1sysW6aqDV rM9Pc8ETY+60Lb5j0WPKvqK0oBcDSXp4XwIIfjD8g6rAUfjG4lsnYnTjzw7TWUwx5R Sc09hyETKCbzTu8UPpjPYIx9RbBx7EVqq7DnneGg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sashiko , Christoph Hellwig , Eric Biggers Subject: [PATCH 6.18 527/675] fscrypt: Add missing superblock check in find_or_insert_direct_key() Date: Thu, 30 Jul 2026 16:14:17 +0200 Message-ID: <20260730141456.345737387@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141445.110192266@linuxfoundation.org> References: <20260730141445.110192266@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Biggers commit b5fa40226e71c17847b9ff2816c6ca4133d0d994 upstream. The legacy 'fscrypt_direct_keys' table caches master keys that are used by v1 encryption policies that have FSCRYPT_POLICY_FLAG_DIRECT_KEY. It's just a global table for all filesystems (since the keys can be provided by the legacy process-subscribed keyrings mechanism, which makes it difficult to reuse super_block::s_master_keys). The entries in it ('struct fscrypt_direct_key') do contain a super_block pointer, though, for passing to fscrypt_destroy_inline_crypt_key() when the last inode that references the key is evicted. However, when finding the fscrypt_direct_key for an inode, we weren't actually comparing the super_block pointer. As a result, inodes with different super_blocks could point to the same fscrypt_direct_key. That could extend the lifetime of a fscrypt_direct_key beyond the super_block it points to, causing a use-after-free later. Fix this by creating distinct fscrypt_direct_key structs for distinct super_block structs. Note that this problem doesn't exist in the v2 policy equivalent ("per-mode keys"), since the data structures there are per super_block. Fixes: 22e9947a4b2b ("fscrypt: stop holding extra request_queue references") Cc: stable@vger.kernel.org Reported-by: Sashiko Closes: https://sashiko.dev/#/patchset/20260717044303.425265-1-ebiggers%40kernel.org Reviewed-by: Christoph Hellwig Link: https://patch.msgid.link/20260719033120.122120-1-ebiggers@kernel.org Signed-off-by: Eric Biggers Signed-off-by: Greg Kroah-Hartman --- fs/crypto/keysetup_v1.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) --- a/fs/crypto/keysetup_v1.c +++ b/fs/crypto/keysetup_v1.c @@ -190,13 +190,19 @@ find_or_insert_direct_key(struct fscrypt if (memcmp(ci->ci_policy.v1.master_key_descriptor, dk->dk_descriptor, FSCRYPT_KEY_DESCRIPTOR_SIZE) != 0) continue; + /* The sb is used at eviction time, so it must be the same. */ + if (ci->ci_inode->i_sb != dk->dk_sb) + continue; if (ci->ci_mode != dk->dk_mode) continue; if (!fscrypt_is_key_prepared(&dk->dk_key, ci)) continue; if (crypto_memneq(raw_key, dk->dk_raw, ci->ci_mode->keysize)) continue; - /* using existing tfm with same (descriptor, mode, raw_key) */ + /* + * Use an existing prepared key with the same (descriptor, sb, + * mode, inlinecrypt, raw_key) combination. + */ refcount_inc(&dk->dk_refcount); spin_unlock(&fscrypt_direct_keys_lock); free_direct_key(to_insert);