From nobody Thu Oct 07 21:18:07 2021 X-Original-To: dev-commits-src-main@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 3A86E12BE8A0; Thu, 7 Oct 2021 21:18:08 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4HQPLS1CL4z54pc; Thu, 7 Oct 2021 21:18:08 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 0970E1A9D0; Thu, 7 Oct 2021 21:18:08 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.16.1/8.16.1) with ESMTP id 197LI7om090112; Thu, 7 Oct 2021 21:18:07 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.16.1/8.16.1/Submit) id 197LI7gw090111; Thu, 7 Oct 2021 21:18:07 GMT (envelope-from git) Date: Thu, 7 Oct 2021 21:18:07 GMT Message-Id: <202110072118.197LI7gw090111@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Mitchell Horne Subject: git: 4a9f2f8b07c2 - main - riscv: handle page faults in the unmappable region List-Id: Commit messages for the main branch of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-main List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-dev-commits-src-main@freebsd.org X-BeenThere: dev-commits-src-main@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: mhorne X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: 4a9f2f8b07c2d1a1c12f4aabdccd36f56b20cfda Auto-Submitted: auto-generated X-ThisMailContainsUnwantedMimeParts: N The branch main has been updated by mhorne: URL: https://cgit.FreeBSD.org/src/commit/?id=4a9f2f8b07c2d1a1c12f4aabdccd36f56b20cfda commit 4a9f2f8b07c2d1a1c12f4aabdccd36f56b20cfda Author: Mitchell Horne AuthorDate: 2021-10-07 21:05:38 +0000 Commit: Mitchell Horne CommitDate: 2021-10-07 21:12:17 +0000 riscv: handle page faults in the unmappable region When handling a kernel page fault, check explicitly that stval resides in either the user or kernel address spaces, and make the page fault fatal if not. Otherwise, a properly crafted address may appear to pmap_fault() as a valid and present page in the kernel map, causing the page fault to be retried continuously. This is mainly due to the fact that the upper bits of virtual addresses are not validated by most of the pmap code. Faults of this nature should only occur due to some kind of bug in the kernel, but it is best to handle them gracefully when they do. Handle user page faults in the same way, sending a SIGSEGV immediately when a malformed address is encountered. Add an assertion to pmap_l1(), which should help catch other bugs of this kind that make it this far. Reviewed by: jrtc27, markj MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D31208 --- sys/riscv/include/vmparam.h | 4 ++++ sys/riscv/riscv/pmap.c | 2 ++ sys/riscv/riscv/trap.c | 8 ++++++++ 3 files changed, 14 insertions(+) diff --git a/sys/riscv/include/vmparam.h b/sys/riscv/include/vmparam.h index 94782da779f7..4ed95def2caa 100644 --- a/sys/riscv/include/vmparam.h +++ b/sys/riscv/include/vmparam.h @@ -186,6 +186,10 @@ #define VM_MINUSER_ADDRESS (VM_MIN_USER_ADDRESS) #define VM_MAXUSER_ADDRESS (VM_MAX_USER_ADDRESS) +/* Check if an address resides in a mappable region. */ +#define VIRT_IS_VALID(va) \ + (((va) < VM_MAX_USER_ADDRESS) || ((va) >= VM_MIN_KERNEL_ADDRESS)) + #define KERNBASE (VM_MIN_KERNEL_ADDRESS) #define SHAREDPAGE (VM_MAXUSER_ADDRESS - PAGE_SIZE) #define USRSTACK SHAREDPAGE diff --git a/sys/riscv/riscv/pmap.c b/sys/riscv/riscv/pmap.c index df80f07df0ca..0918325c13fb 100644 --- a/sys/riscv/riscv/pmap.c +++ b/sys/riscv/riscv/pmap.c @@ -351,6 +351,8 @@ static __inline pd_entry_t * pmap_l1(pmap_t pmap, vm_offset_t va) { + KASSERT(VIRT_IS_VALID(va), + ("%s: malformed virtual address %#lx", __func__, va)); return (&pmap->pm_l1[pmap_l1_index(va)]); } diff --git a/sys/riscv/riscv/trap.c b/sys/riscv/riscv/trap.c index 8844638c8204..8eb52fcc5337 100644 --- a/sys/riscv/riscv/trap.c +++ b/sys/riscv/riscv/trap.c @@ -200,6 +200,11 @@ page_fault_handler(struct trapframe *frame, int usermode) goto fatal; if (usermode) { + if (!VIRT_IS_VALID(stval)) { + call_trapsignal(td, SIGSEGV, SEGV_MAPERR, (void *)stval, + frame->tf_scause & SCAUSE_CODE); + goto done; + } map = &td->td_proc->p_vmspace->vm_map; } else { /* @@ -208,6 +213,9 @@ page_fault_handler(struct trapframe *frame, int usermode) */ intr_enable(); + if (!VIRT_IS_VALID(stval)) + goto fatal; + if (stval >= VM_MAX_USER_ADDRESS) { map = kernel_map; } else {