From patchwork Thu Jan 11 04:08:32 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexey Kardashevskiy X-Patchwork-Id: 858762 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=nongnu.org (client-ip=2001:4830:134:3::11; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3zHC7C1yM4z9sNc for ; Thu, 11 Jan 2018 15:09:11 +1100 (AEDT) Received: from localhost ([::1]:38063 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eZUAv-0006no-9g for incoming@patchwork.ozlabs.org; Wed, 10 Jan 2018 23:09:09 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54892) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eZUAS-0006nH-S7 for qemu-devel@nongnu.org; Wed, 10 Jan 2018 23:08:41 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eZUAP-0005Gr-ND for qemu-devel@nongnu.org; Wed, 10 Jan 2018 23:08:40 -0500 Received: from ozlabs.ru ([107.173.13.209]:49080) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eZUAP-0005F8-Hq; Wed, 10 Jan 2018 23:08:37 -0500 Received: from vpl1.ozlabs.ibm.com (localhost [IPv6:::1]) by ozlabs.ru (Postfix) with ESMTP id 2A4953A6000A; Wed, 10 Jan 2018 23:08:16 -0500 (EST) From: Alexey Kardashevskiy To: qemu-devel@nongnu.org Date: Thu, 11 Jan 2018 15:08:32 +1100 Message-Id: <20180111040832.28383-1-aik@ozlabs.ru> X-Mailer: git-send-email 2.11.0 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 107.173.13.209 Subject: [Qemu-devel] [PATCH qemu] target/ppc: Yet another fix for KVM-HV HPTE accessors X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Alexey Kardashevskiy , qemu-ppc@nongnu.org, David Gibson Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" As stated in the 1ad9f0a464fe commit log, the returned entries are not a while PTEG. It was not a problem before 1ad9f0a464fe as it would read a single record assuming it contains a whole PTEG but now the code tries reading the entire PTEG and "if ((n - i) < invalid)" produces negative values which then are converted to size_t for memset() and that throws seg fault. This fixes the math. While here, fix the last @i increment as well. Fixes: 1ad9f0a464fe "target/ppc: Fix KVM-HV HPTE accessors" Signed-off-by: Alexey Kardashevskiy --- Record #0: (gdb) p *hdr $13 = { index = , n_valid = 0x1, n_invalid = 0x6 } Record #1: (gdb) p *hdr $18 = { index = , n_valid = 0x2, n_invalid = 0x6 } i.e. in the second iteration of the loop right before "if ((n - i) < invalid)": (gdb) p n $16 = 0x8 (gdb) p i $17 = 0x9 and @invalid becomes -1. --- target/ppc/kvm.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c index 0566af7..c2dea81 100644 --- a/target/ppc/kvm.c +++ b/target/ppc/kvm.c @@ -2657,21 +2657,24 @@ void kvmppc_read_hptes(ppc_hash_pte64_t *hptes, hwaddr ptex, int n) hdr = (struct kvm_get_htab_header *)buf; while ((i < n) && ((char *)hdr < (buf + rc))) { - int invalid = hdr->n_invalid; + int invalid = hdr->n_invalid, valid = hdr->n_valid; if (hdr->index != (ptex + i)) { hw_error("kvmppc_read_hptes: Unexpected HPTE index %"PRIu32 " != (%"HWADDR_PRIu" + %d", hdr->index, ptex, i); } - memcpy(hptes + i, hdr + 1, HASH_PTE_SIZE_64 * hdr->n_valid); - i += hdr->n_valid; + if (n - i < valid) { + valid = n - i; + } + memcpy(hptes + i, hdr + 1, HASH_PTE_SIZE_64 * valid); + i += valid; if ((n - i) < invalid) { invalid = n - i; } memset(hptes + i, 0, invalid * HASH_PTE_SIZE_64); - i += hdr->n_invalid; + i += invalid; hdr = (struct kvm_get_htab_header *) ((char *)(hdr + 1) + HASH_PTE_SIZE_64 * hdr->n_valid);