Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 428D8C433FE for ; Thu, 30 Dec 2021 19:16:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241946AbhL3TQZ (ORCPT ); Thu, 30 Dec 2021 14:16:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46606 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241857AbhL3TQU (ORCPT ); Thu, 30 Dec 2021 14:16:20 -0500 Received: from out2.migadu.com (out2.migadu.com [IPv6:2001:41d0:2:aacc::]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B82DBC06173E for ; Thu, 30 Dec 2021 11:16:20 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1640891779; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=wa5dnCuIAAFZXmbcwU/lwh0PzifCMo4jVhMhMRLXZ80=; b=be7gQ6BJxVXB67WDKBd1nVRXm7qrNt980OSIm0sZvaVwRfeIDzOCt6ojTVwmz6pzlR9ugS LtVsCauLj2srfIq0oKYGHUCfJ0dx2GkuDbF9gu0G5p2ICarf4H7RWov0VyKGRBiv1kboUl 9G+5U5+DVh7RFyS82sULQb89o8S9b3I= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Andrey Ryabinin , kasan-dev@googlegroups.com, linux-mm@kvack.org, Vincenzo Frascino , Catalin Marinas , Will Deacon , Mark Rutland , linux-arm-kernel@lists.infradead.org, Peter Collingbourne , Evgenii Stepanov , linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH mm v5 32/39] kasan, arm64: don't tag executable vmalloc allocations Date: Thu, 30 Dec 2021 20:14:57 +0100 Message-Id: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: linux.dev Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andrey Konovalov Besides asking vmalloc memory to be executable via the prot argument of __vmalloc_node_range() (see the previous patch), the kernel can skip that bit and instead mark memory as executable via set_memory_x(). Once tag-based KASAN modes start tagging vmalloc allocations, executing code from such allocations will lead to the PC register getting a tag, which is not tolerated by the kernel. Generic kernel code typically allocates memory via module_alloc() if it intends to mark memory as executable. (On arm64 module_alloc() uses __vmalloc_node_range() without setting the executable bit). Thus, reset pointer tags of pointers returned from module_alloc(). However, on arm64 there's an exception: the eBPF subsystem. Instead of using module_alloc(), it uses vmalloc() (via bpf_jit_alloc_exec()) to allocate its JIT region. Thus, reset pointer tags of pointers returned from bpf_jit_alloc_exec(). Resetting tags for these pointers results in untagged pointers being passed to set_memory_x(). This causes conflicts in arithmetic checks in change_memory_common(), as vm_struct->addr pointer returned by find_vm_area() is tagged. Reset pointer tag of find_vm_area(addr)->addr in change_memory_common(). Signed-off-by: Andrey Konovalov Acked-by: Catalin Marinas --- Changes v3->v4: - Reset pointer tag in change_memory_common(). Changes v2->v3: - Add this patch. --- arch/arm64/kernel/module.c | 3 ++- arch/arm64/mm/pageattr.c | 2 +- arch/arm64/net/bpf_jit_comp.c | 3 ++- 3 files changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c index d3a1fa818348..f2d4bb14bfab 100644 --- a/arch/arm64/kernel/module.c +++ b/arch/arm64/kernel/module.c @@ -63,7 +63,8 @@ void *module_alloc(unsigned long size) return NULL; } - return p; + /* Memory is intended to be executable, reset the pointer tag. */ + return kasan_reset_tag(p); } enum aarch64_reloc_op { diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c index a3bacd79507a..64e985eaa52d 100644 --- a/arch/arm64/mm/pageattr.c +++ b/arch/arm64/mm/pageattr.c @@ -85,7 +85,7 @@ static int change_memory_common(unsigned long addr, int numpages, */ area = find_vm_area((void *)addr); if (!area || - end > (unsigned long)area->addr + area->size || + end > (unsigned long)kasan_reset_tag(area->addr) + area->size || !(area->flags & VM_ALLOC)) return -EINVAL; diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index 07aad85848fa..381a67922c2d 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -1147,7 +1147,8 @@ u64 bpf_jit_alloc_exec_limit(void) void *bpf_jit_alloc_exec(unsigned long size) { - return vmalloc(size); + /* Memory is intended to be executable, reset the pointer tag. */ + return kasan_reset_tag(vmalloc(size)); } void bpf_jit_free_exec(void *addr) -- 2.25.1