From nobody Tue Apr 30 20:45:21 2024 Delivered-To: importer@patchew.org Received-SPF: temperror (zoho.com: Error in retrieving data from DNS) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=temperror (zoho.com: Error in retrieving data from DNS) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (208.118.235.17 [208.118.235.17]) by mx.zohomail.com with SMTPS id 1508228287804701.4828570651516; Tue, 17 Oct 2017 01:18:07 -0700 (PDT) Received: from localhost ([::1]:37149 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1e4N4L-0000XB-Hg for importer@patchew.org; Tue, 17 Oct 2017 04:17:45 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57910) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1e4N39-0008Si-P1 for qemu-devel@nongnu.org; Tue, 17 Oct 2017 04:16:32 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1e4N36-0007pP-K5 for qemu-devel@nongnu.org; Tue, 17 Oct 2017 04:16:31 -0400 Received: from 14.mo4.mail-out.ovh.net ([46.105.40.29]:36789) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1e4N36-0007oY-Ee for qemu-devel@nongnu.org; Tue, 17 Oct 2017 04:16:28 -0400 Received: from player159.ha.ovh.net (b9.ovh.net [213.186.33.59]) by mo4.mail-out.ovh.net (Postfix) with ESMTP id EF80AE8CCC for ; Tue, 17 Oct 2017 10:16:26 +0200 (CEST) Received: from bahia.lan (gar31-1-82-66-74-139.fbx.proxad.net [82.66.74.139]) (Authenticated sender: groug@kaod.org) by player159.ha.ovh.net (Postfix) with ESMTPA id A0BF24800AA; Tue, 17 Oct 2017 10:16:22 +0200 (CEST) From: Greg Kurz To: qemu-devel@nongnu.org Date: Tue, 17 Oct 2017 10:16:22 +0200 Message-ID: <150822818243.26242.12993827911736928961.stgit@bahia.lan> User-Agent: StGit/0.17.1-46-g6855-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Ovh-Tracer-Id: 13572160427163818350 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedttddrudeggddtfecutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfqggfjpdevjffgvefmvefgnecuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 46.105.40.29 Subject: [Qemu-devel] [PATCH v3] monitor: fix dangling CPU pointer 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: Igor Mammedov , qemu-ppc@nongnu.org, Markus Armbruster , "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_6 Z_629925259 SPT_0 If a CPU selected with the "cpu" command is hot-unplugged then "info cpus" causes QEMU to exit: (qemu) device_del cpu1 (qemu) info cpus qemu:qemu_cpu_kick_thread: No such process This happens because "cpu" stores the pointer to the selected CPU into the monitor structure. When the CPU is hot-unplugged, we end up with a dangling pointer. The "info cpus" command then does: hmp_info_cpus() monitor_get_cpu_index() mon_get_cpu() cpu_synchronize_state() <--- called with dangling pointer This could cause a QEMU crash as well. This patch switches the monitor to store the QOM path instead of a pointer to the current CPU. The path is then resolved when needed. If the resolution fails, we assume that the CPU was removed and the path is resetted to the default (ie, path of first_cpu). Reported-by: Satheesh Rajendran Suggested-by: Igor Mammedov Signed-off-by: Greg Kurz Reviewed-by: Igor Mammedov --- v3: - drop irrelevant paragraph about object_resolve_path() from the changelog v2: - use object_resolve_path_type() - add Reported-by tag --- monitor.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/monitor.c b/monitor.c index fe0d1bdbb461..ce577e46e568 100644 --- a/monitor.c +++ b/monitor.c @@ -200,7 +200,7 @@ struct Monitor { =20 ReadLineState *rs; MonitorQMP qmp; - CPUState *mon_cpu; + gchar *mon_cpu_path; BlockCompletionFunc *password_completion_cb; void *password_opaque; mon_cmd_t *cmd_table; @@ -579,6 +579,7 @@ static void monitor_data_init(Monitor *mon) =20 static void monitor_data_destroy(Monitor *mon) { + g_free(mon->mon_cpu_path); qemu_chr_fe_deinit(&mon->chr, false); if (monitor_is_qmp(mon)) { json_message_parser_destroy(&mon->qmp.parser); @@ -1047,20 +1048,32 @@ int monitor_set_cpu(int cpu_index) if (cpu =3D=3D NULL) { return -1; } - cur_mon->mon_cpu =3D cpu; + g_free(cur_mon->mon_cpu_path); + cur_mon->mon_cpu_path =3D object_get_canonical_path(OBJECT(cpu)); return 0; } =20 CPUState *mon_get_cpu(void) { - if (!cur_mon->mon_cpu) { + CPUState *cpu; + + if (cur_mon->mon_cpu_path) { + cpu =3D (CPUState *) object_resolve_path_type(cur_mon->mon_cpu_pat= h, + TYPE_CPU, NULL); + if (!cpu) { + g_free(cur_mon->mon_cpu_path); + cur_mon->mon_cpu_path =3D NULL; + } + } + if (!cur_mon->mon_cpu_path) { if (!first_cpu) { return NULL; } monitor_set_cpu(first_cpu->cpu_index); + cpu =3D first_cpu; } - cpu_synchronize_state(cur_mon->mon_cpu); - return cur_mon->mon_cpu; + cpu_synchronize_state(cpu); + return cpu; } =20 CPUArchState *mon_get_cpu_env(void)