From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f199.google.com (mail-pl1-f199.google.com [209.85.214.199]) (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 B56164A4834 for ; Tue, 1 Sep 2026 20:53:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788295982; cv=none; b=S0s4Ce+tsEpxRC1ZMfF4Z/84s5EZH4bZpHbEqsTUA/yK7O+vc5nDB3cA4k+Lr0DHm9cDAxQYGZiehhrFvwokZ5TWfg5SWdMDSdGRbsDpK6Af4kfb90cx5dkIb33PJ67NLV9sXYt1LKOP6CUI1gWhFoIbXhLo4/V6w1FOknFfhUI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788295982; c=relaxed/simple; bh=8YxYBVKp4QC6MS58T6jznUoadNYscBAXK9umwSVzAlk=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=ihixsoJyFb9S3bCZoQaFQsIIuMrrEGxX0/wCZqQE8w83FZiGuWI7yqrNSOlaTnqOY/3Lextzh/n7C00NCsyCV04jFKCwOWu//8g/4u5YNW+J+NP0ouEt+LfqSsE0dbfbKiQW5b/TNDB5nrTiKuOzF2Hn8qfY3MTNljJjBjWwvPQ= 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=g6jEOv98; arc=none smtp.client-ip=209.85.214.199 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="g6jEOv98" Received: by mail-pl1-f199.google.com with SMTP id d9443c01a7336-2d6fed0652bso2667545ad.2 for ; Tue, 01 Sep 2026 13:53:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1788295980; x=1788900780; 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=WWyWDWfLZFwic6F4ZvVl11QlqA6Vmuy0wQNwElQAh38=; b=g6jEOv98s7WACaPPo0Hi3snTyvFMOmljYiq7Q1vAkX/DOnCijmTlfhpyAgksagCWeE vnpnk2SPP4r+k+9Jibobb5ApoSfQG/Org1KTLdRJyc1/fR58qXIKBsYO8SwuGnk3VwrT twNm5x+q/9KQ4cDmM8ihv0lSkFWZrKSiyGm73BkhykKg7SiK78BGTs6KPuOSVcnVwELV g6deda675qu4KpUAk2WZPOZURYXZhCy7QT9oNbVYFLLHj9SVQ2Y6aOjs+Ltl0wLPeCJT iNkVAIzDjvJMYxcoifu+UvOZ3OQ4Ma3CBcsRC1Hpsi2cijCI3tJaQelNT86LbnL+bzKf S4tA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788295980; x=1788900780; 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=WWyWDWfLZFwic6F4ZvVl11QlqA6Vmuy0wQNwElQAh38=; b=h7oVTzVNDXLTMYIpJ/SyOc0f577DyM0+NH4wzb4HIbSjrMKORynYiPoREUBdnFpmYB VwrJWww9NsqrCgbnfSbUCPz6d0rGPxXEImPnRt3OgpgC7iROrUo0vfIot1bkj0B89+Vb JfyJOF+l2WdlQBOV0IrK++X2lirYRm0j4xnjOevQCQ0gWJwdCgvOkdQMrfY3HS4PDFU+ S/SslzAc5gBhwJUtI8/BzjHde9VM7cP5n98/omDQZbsLclv5rCRBAhfQoTZf3HYqptxH ymsLTm2sF3I887lwXGOyp6C1NpK+SSQcn1X+EruFVanviy1PgZgBMsG8CZ2SzhfVniJJ eXNg== X-Forwarded-Encrypted: i=1; AKwUvBxO3zXrhZYVW81W5c/88JlrSsWdJVCcJKGCC8BxRkM7WZ4KpwnERe/v8hsLTUspxBska75j8e8=@vger.kernel.org X-Gm-Message-State: AFuF++noTb8/tqS1ZZF3ePI3eUEg0T/DDwwKlp9TDxX67dklY8brS4eN an9aS/p5GjPI8JVC59a5AyiaNJDoDo/TzTsaqjtZcWNZJCWTtYOiTaqscuRGuSAjxrQc03p5/k9 3jpff8Ldne8E2tw== X-Received: from dyw18.prod.google.com ([2002:a05:7300:8812:b0:328:4817:a473]) (user=cmllamas job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:11c8:b0:2d9:26b3:547 with SMTP id d9443c01a7336-2d926b30c76mr207766345ad.20.1788295979822; Tue, 01 Sep 2026 13:52:59 -0700 (PDT) Date: Tue, 1 Sep 2026 20:52:44 +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: <20260901205250.1638304-5-cmllamas@google.com> Subject: [PATCH v4 4/7] rust_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 , Benno Lossin , Gary Guo Cc: kernel-team@android.com, linux-kernel@vger.kernel.org, Suren Baghdasaryan , stable@vger.kernel.org, Sashiko , "open list:RUST [PIN-INIT]:Keyword:bpin-initb|pin_initb|PinInit" 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: eafedbc7c050 ("rust_binder: add Rust 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/page_range.rs | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/drivers/android/binder/page_range.rs b/drivers/android/binder/page_range.rs index 52ffbf3504e7..d260b009c184 100644 --- a/drivers/android/binder/page_range.rs +++ b/drivers/android/binder/page_range.rs @@ -24,7 +24,7 @@ use kernel::{ bindings, error::Result, - ffi::{c_ulong, c_void}, + ffi::{c_int, c_ulong, c_void}, mm::{virt, Mm, MmWithUser}, new_mutex, new_spinlock, page::{Page, PAGE_SHIFT, PAGE_SIZE}, @@ -144,8 +144,17 @@ pub(crate) struct ShrinkablePageRange { _pin: PhantomPinned, } -// We do not define any ops. For now, used only to check identity of vmas. -static BINDER_VM_OPS: AssertSync = AssertSync(pin_init::zeroed()); +unsafe extern "C" fn binder_vma_may_split(_: *mut bindings::vm_area_struct, _: c_ulong) -> c_int { + EINVAL.to_errno() +} + +static BINDER_VM_OPS: AssertSync = { + let ops = bindings::vm_operations_struct { + may_split: Some(binder_vma_may_split), + ..pin_init::zeroed() + }; + AssertSync(ops) +}; // To ensure that we do not accidentally install pages into or zap pages from the wrong vma, we // check its vm_ops and private data before using it. -- 2.55.0.966.g6673acef38-goog