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 792AD439F7F; Mon, 17 Aug 2026 13:50:05 +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=1786974610; cv=none; b=N6SaIIwMFmeOKvoqCccn2XOzcGB6JpU6ueTLVZ5qzlfhk4TNv3L5y/3EnA3SjHm7F6uYqQniLCmj1mU95Cuiw8VVW4QazAukvQyjLubhLGNcVma6yUoud17SQwfDKGc4SM+cD4OJ3GMZQ98vSPT49aGZmIiAb0N6ESAIu+K1dG8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786974610; c=relaxed/simple; bh=G0qLG/yQ4Y0WFMsXpM1XRe118Kqd+eF5Jjw0zfnKuLo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CLkmA9S/WZSqE8E37kp4rCGBOjNC/wBVtRTDS0SrnQmSZPcgpR8FQ6zhA9MuaZYwf22eNLI+4GpvgIJi34tfuXM+who2+DIwjqs7Svky4ZpkedaNchJCzr8jZwK2VUbM/D8I/k9eQo8UybusDweK86snITL0Nc0DizsNKbq4+ks= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=M6RSzDvF; 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="M6RSzDvF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 704C71F000E9; Mon, 17 Aug 2026 13:50:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786974603; bh=u+A3/g0Vvwu3jzFPMyyNU1qO7at2QqF/YW+Bi4ma/H0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=M6RSzDvFU3+emcejT9I1T2BNTiSCqlcbvH7RSvBvoltKtDS3213NBiwJXYEiQQ21F 7SR5x4wKg5kyMP400r+6KijY8SwyhliXbVVMYkASB/RA4vu5zqaxdtlwi47OolKPDK 2yEliKJRnOLZ4vNV1j3GfJx6tg0QaCP1fSDQIYaI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Biggers , Kumar Kartikeya Dwivedi , Song Liu Subject: [PATCH 7.1 263/271] fsverity: Fix bpf_get_fsverity_digest() dynptr assumptions Date: Mon, 17 Aug 2026 15:33:08 +0200 Message-ID: <20260817132547.544441787@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260817132536.752504388@linuxfoundation.org> References: <20260817132536.752504388@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 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Biggers commit 3e8ec7c0387273329374f5c7bd61f5f38af71fe1 upstream. The BPF verifier and the dynptr abstraction ensure that the memory space referenced by a dynptr remains valid. They do not, however, provide any guarantee that the contents of the memory are stable. kfuncs are expected to remain memory-safe even if concurrent modifications occur. bpf_get_fsverity_digest() didn't follow that: it could crash if arg->digest_size was concurrently modified. Fix that by using the known-good value hash_alg->digest_size instead. Also widen 'dynptr_sz' and 'out_digest_sz' to u64 to match the return type of __bpf_dynptr_size(). It doesn't appear that it can actually be more than INT_MAX currently (since __bpf_dynptr_data_rw() excludes file-based pointers), but the correct type might as well be used. Fixes: 67814c00de31 ("bpf, fsverity: Add kfunc bpf_get_fsverity_digest") Signed-off-by: Eric Biggers Acked-by: Kumar Kartikeya Dwivedi Acked-by: Song Liu Cc: stable@vger.kernel.org Link: https://lore.kernel.org/bpf/20260803181232.14743-2-ebiggers@kernel.org Signed-off-by: Kumar Kartikeya Dwivedi Signed-off-by: Greg Kroah-Hartman --- fs/verity/measure.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) --- a/fs/verity/measure.c +++ b/fs/verity/measure.c @@ -122,11 +122,11 @@ __bpf_kfunc int bpf_get_fsverity_digest( { struct bpf_dynptr_kern *digest_ptr = (struct bpf_dynptr_kern *)digest_p; const struct inode *inode = file_inode(file); - u32 dynptr_sz = __bpf_dynptr_size(digest_ptr); + u64 dynptr_sz = __bpf_dynptr_size(digest_ptr); struct fsverity_digest *arg; const struct fsverity_info *vi; const struct fsverity_hash_alg *hash_alg; - int out_digest_sz; + u64 out_digest_sz; if (dynptr_sz < sizeof(struct fsverity_digest)) return -EINVAL; @@ -150,11 +150,13 @@ __bpf_kfunc int bpf_get_fsverity_digest( out_digest_sz = dynptr_sz - sizeof(struct fsverity_digest); /* copy digest */ - memcpy(arg->digest, vi->file_digest, min_t(int, hash_alg->digest_size, out_digest_sz)); + memcpy(arg->digest, vi->file_digest, + min(hash_alg->digest_size, out_digest_sz)); /* fill the extra buffer with zeros */ if (out_digest_sz > hash_alg->digest_size) - memset(arg->digest + arg->digest_size, 0, out_digest_sz - hash_alg->digest_size); + memset(arg->digest + hash_alg->digest_size, 0, + out_digest_sz - hash_alg->digest_size); return 0; }