From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f200.google.com (mail-pl1-f200.google.com [209.85.214.200]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 68BFC4A3853 for ; Tue, 1 Sep 2026 20:52:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.200 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788295980; cv=none; b=c3/HGsOdLDFqDsG0RM8bG5Bn6jJrdDRcIEOGkl6hYF1iZp+5beCT26DlekTgTa8UAvux/FME+DsRuvMMisUscgE3JgpZZTpxGv9U+bCj6zPldRRhCmTKIw83/Pj9F+boTZI5ef1HIIT+rmNwkraM6avcWAmw2jfIgOmi4AVcF+M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788295980; c=relaxed/simple; bh=GPmeVGMLIoZoIlDJwvRRrzHCCviiWSVdzdWd0kwp7eo=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=DD3B0TW7GVhJFzrvfm513mSBWx8GcAyTHGXH+j+xMqflWRxzLeBJ9glm49w8gKDQJ/S8IFFi1hbKGO2hc3M1/cidSDr9eOVwNIgj6bYbxuItZGJ3NaTaI8KVDYbQyUC9O0B4/byKHb5LtGJxi7NfftJ7mJZkujOI2mFGq0RV2Qs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--cmllamas.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=m5ecM0yJ; arc=none smtp.client-ip=209.85.214.200 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--cmllamas.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="m5ecM0yJ" Received: by mail-pl1-f200.google.com with SMTP id d9443c01a7336-2d7151120d6so3580455ad.3 for ; Tue, 01 Sep 2026 13:52:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1788295979; x=1788900779; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=efterSwzpT8WmqwjvTJaX4ZNpH8DVSU8cX8allgguTQ=; b=m5ecM0yJsyCkqUMj/OhmTLDBCeK8fq5schsf/1klusppv0XbQdHhKHewW4Ggp8Ui2T ViDRJVyaHxRPmK5MUVAM7BgDdlfD1BG6kTAMMxHCwl/nBs7WtCLF5k6M4tEOHONSRbYT 8f3O0FXv8hJ20QpEsYW7Fkp6kKkIkzLhb59LMHFxmA0leEq8R6WoEtPnMrFD4oJufCk1 YwkmoyPJzxDs+7wrehAM7XqU1lKzrP6PUrhJLwgVC35JTXsbKJDGh187joiSm6xY/7xa jMmHZvNOUww9OsBNSIOcnIolP1VbavTeHvIpdacG+rKHVL3L3Hvyxw59B/RTyxRH+TlY N8QQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788295979; x=1788900779; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=efterSwzpT8WmqwjvTJaX4ZNpH8DVSU8cX8allgguTQ=; b=dqDhSSqlQ1VoBDp9+IAwednAiICRs7rqiQyQz4qaBUXkA4Aw9qcixcybjRK8TzHMgT KXO/QNEWz96n5sH5ZITlSJD8JS2f9lRTuxhLedVVCFq7hTbpy8PuxXsMG+u2hsecmtTU uWCJtwC2YXGU3NuU8DRE8DFZmRPkHkkSQsNKbwpCUwZeYEjTD14oZ4yB5kU9n0emK2Ut ADLhzqdC9n9sKW+su88bR/EfGVxP8GKajlWeqqWEs5aoo3bo9lihyE063HyqikGzBJtO wNzaN3SuDQZ1XuwB85OQGTGdr6OCE2Sel8pL1QRVDLpEyF9VLlR7yPnJwyEgnPVIZ3cI b6yw== X-Forwarded-Encrypted: i=1; AKwUvBz7Tm1OooU7oUR78AIXM5y0i1pOak2ovE/NxPdfOCxmfD0lH28/QyIRH+/8EB9n8P9H/X73KnU=@vger.kernel.org X-Gm-Message-State: AFuF++lgTd2ZTW2mxueUQ6QHvfvIRvfGABUJKCr4TUR2ve4RowZcYNXu 5Fnll87zW7uDrf0sXvYVef3QvUdZbgbWoEulr6qJePPzEOBbLFQz0L8GyAtSSoywLMTCdWTFnou nLrzz+HIKPlUEeA== X-Received: from dld23.prod.google.com ([2002:a05:7022:317:b0:13b:9d65:a542]) (user=cmllamas job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:394c:b0:398:9bd4:d12 with SMTP id 98e67ed59e1d1-39907e4ada0mr17485453a91.17.1788295978602; Tue, 01 Sep 2026 13:52:58 -0700 (PDT) Date: Tue, 1 Sep 2026 20:52:43 +0000 In-Reply-To: <20260901205250.1638304-1-cmllamas@google.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260901205250.1638304-1-cmllamas@google.com> X-Mailer: git-send-email 2.55.0.966.g6673acef38-goog Message-ID: <20260901205250.1638304-4-cmllamas@google.com> Subject: [PATCH v4 3/7] binder: forbid vma splitting From: Carlos Llamas To: Greg Kroah-Hartman , "=?UTF-8?q?Arve=20Hj=C3=B8nnev=C3=A5g?=" , Todd Kjos , Christian Brauner , Carlos Llamas , Alice Ryhl Cc: kernel-team@android.com, linux-kernel@vger.kernel.org, Suren Baghdasaryan , stable@vger.kernel.org, Sashiko Content-Type: text/plain; charset="UTF-8" Binder does not support splitting its mappings. Allowing so, leads to potential attacks that stem from a partial munmap(), such as closing the tail range and replacing it with a new mapping. Close the loophole by explicitly rejecting vma splitting. Cc: stable@vger.kernel.org Fixes: 457b9a6f09f0 ("Staging: android: add binder driver") Reported-by: Sashiko Closes: https://sashiko.dev/#/patchset/20260901163521.1355535-1-cmllamas@google.com?part=2 Signed-off-by: Carlos Llamas --- drivers/android/binder.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 1b492ed48ea6..185128577829 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -6032,10 +6032,16 @@ VISIBLE_IF_KUNIT vm_fault_t binder_vm_fault(struct vm_fault *vmf) } EXPORT_SYMBOL_IF_KUNIT(binder_vm_fault); +static int binder_vma_may_split(struct vm_area_struct *vma, unsigned long addr) +{ + return -EINVAL; +} + static const struct vm_operations_struct binder_vm_ops = { .open = binder_vma_open, .close = binder_vma_close, .fault = binder_vm_fault, + .may_split = binder_vma_may_split, }; static int binder_mmap(struct file *filp, struct vm_area_struct *vma) -- 2.55.0.966.g6673acef38-goog