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 3AF6C1EA84; Sun, 19 Jul 2026 03:33:25 +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=1784432007; cv=none; b=Hhpj7pyIJMHLWIn9DEaASIb5h5clH2hR6MDdZ2kmEnUAY+6AdF+qfNbEEps+qvN4ZyCG1YZslPIa7LYtQL0yUIyvrFilSeoJMzB03j90sqQHD1x5gtpcPnDhEz1DguuwnqJDhxIAJaL34WMJtUIM2+O9oH4MMbnlKtjMJnZysZY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784432007; c=relaxed/simple; bh=auueHM22gwk3ZoyB7F0PqaSJr6Ppc2lH1hGfisJSHt4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=BsMmHAypbucYmsMqZ5+W6bUoso526bTTearQ4LzO/eoz7sS8fp2sEdbA59GXCuT5MkzXAvQTtHSbFbow9qGfOgr0D2fjf3bTEwfOKOy1DGaD21+KcW3ayCGHnVRg2W6faEpJMRnjRRc9VSYpCAqNbgKK7x2m6ra3B6tqajbT5Mg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Prx8SDZ2; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Prx8SDZ2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A62D41F000E9; Sun, 19 Jul 2026 03:33:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784432005; bh=sqXj9cTOh3TCwpf7vuFFoZoI/vAAVMm1ty+3JLUXvsw=; h=From:To:Cc:Subject:Date; b=Prx8SDZ25PdMrI2sbmjqKS/BsY3dljVK30ol7Jr+0+82Zh46J3YKQ7CJMalqtu1gr tmC4m2Gzeke+dagJROuuZ4Z3Gn1x+SBuYDbzYKJlyCgkU/hkz5FAWj71yjTs5KgoBW NOMX9hNCDOH7K3QPTyrQ7riBSuTPdsSVbe+eQMJfCgoGPkV0SlKRCwtbn05GIk79YG PfEmkKbNZ6MTFN0zk3ng92U7CTRGDkZ8Wgy81KBvdKh7kJ9nHTEbhb26/ahKxg6Ryl kO+OoAtB7lD0WZ+e9oQayjgMSLPGZvAycb4eTVlffFecIyai9Hf9QtLN86Z6or1VUk BnFzNovXMgNRA== From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Eric Biggers , stable@vger.kernel.org Subject: [PATCH] fscrypt: Add missing superblock check in find_or_insert_direct_key() Date: Sat, 18 Jul 2026 20:31:20 -0700 Message-ID: <20260719033120.122120-1-ebiggers@kernel.org> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Eric Biggers --- fs/crypto/keysetup_v1.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/crypto/keysetup_v1.c b/fs/crypto/keysetup_v1.c index e6e527c73f167..7e3a58dc4b566 100644 --- a/fs/crypto/keysetup_v1.c +++ b/fs/crypto/keysetup_v1.c @@ -147,13 +147,19 @@ find_or_insert_direct_key(struct fscrypt_direct_key *to_insert, 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); base-commit: f2ec6312bf711369561bdcb22f8a63c0b118c479 -- 2.55.0