From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.90_1) id 1rcoa6-0005lg-Ma for mharc-qemu-trivial@gnu.org; Wed, 21 Feb 2024 10:32:22 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rcoa3-0005Rn-SX for qemu-trivial@nongnu.org; Wed, 21 Feb 2024 10:32:20 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rcl4f-0000AZ-M1 for qemu-trivial@nongnu.org; Wed, 21 Feb 2024 06:47:43 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1708516059; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=hlagwSl2YsZuNFzln+6oCnnPHlq+xDD7OxjiWOTZMyU=; b=hcCONE4lNdi7bMamzMNRCx/UYQ0NKKJBqVyBAd4fXgnU7Hkc6UOELKWJdLsMCqxfmXwPD9 jxDKk1PPyInXMZKy4y6G50dYTgrqfTBVR/OgaHvkxi2aOEu66ixvMfJuaXrfUvn3Hm8sJS t+sY0ZhsXpKoPZajlomrJmu1TDNnSIw= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-361-LUpPYozJM523E6VipHT9CA-1; Wed, 21 Feb 2024 06:47:35 -0500 X-MC-Unique: LUpPYozJM523E6VipHT9CA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id EBD44863063; Wed, 21 Feb 2024 11:47:34 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.192.55]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8E15A20169C6; Wed, 21 Feb 2024 11:47:34 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 7A98721E66D5; Wed, 21 Feb 2024 12:47:33 +0100 (CET) From: Markus Armbruster To: Zhao Liu Cc: Jonathan Cameron , Fan Ni , Laurent Vivier , Alistair Francis , "Edgar E . Iglesias" , Peter Maydell , "Michael S . Tsirkin" , Marcel Apfelbaum , Alex Williamson , =?utf-8?Q?C=C3=A9dric?= Le Goater , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Markus Armbruster , qemu-devel@nongnu.org, qemu-arm@nongnu.org, qemu-trivial@nongnu.org, Zhao Liu Subject: Re: [PATCH 4/6] hw/misc/xlnx-versal-trng: Fix missing ERRP_GUARD() in trng_prop_fault_event_set() In-Reply-To: <20240221094317.994454-5-zhao1.liu@linux.intel.com> (Zhao Liu's message of "Wed, 21 Feb 2024 17:43:15 +0800") References: <20240221094317.994454-1-zhao1.liu@linux.intel.com> <20240221094317.994454-5-zhao1.liu@linux.intel.com> Date: Wed, 21 Feb 2024 12:47:33 +0100 Message-ID: <87ttm2ujhm.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.4 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.05, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-trivial@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 21 Feb 2024 15:32:21 -0000 Zhao Liu writes: > From: Zhao Liu > > As the comment in qapi/error, dereferencing @errp requires > ERRP_GUARD(): > > * = Why, when and how to use ERRP_GUARD() = > * > * Without ERRP_GUARD(), use of the @errp parameter is restricted: > * - It must not be dereferenced, because it may be null. > * - It should not be passed to error_prepend() or > * error_append_hint(), because that doesn't work with &error_fatal. > * ERRP_GUARD() lifts these restrictions. > * > * To use ERRP_GUARD(), add it right at the beginning of the function. > * @errp can then be used without worrying about the argument being > * NULL or &error_fatal. > * > * Using it when it's not needed is safe, but please avoid cluttering > * the source with useless code. > > Currently, since trng_prop_fault_event_set() doesn't get the NULL errp > parameter as a "set" method of object property, it doesn't trigger the > dereference issue. > > To follow the requirement of errp, add missing ERRP_GUARD() in > trng_prop_fault_event_set(). > > Suggested-by: Markus Armbruster > Signed-off-by: Zhao Liu > --- > Suggested by credit: > Markus: Referred his explanation about ERRP_GUARD(). > --- > hw/misc/xlnx-versal-trng.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/hw/misc/xlnx-versal-trng.c b/hw/misc/xlnx-versal-trng.c > index b8111b8b6626..3579348a9d17 100644 > --- a/hw/misc/xlnx-versal-trng.c > +++ b/hw/misc/xlnx-versal-trng.c > @@ -33,6 +33,7 @@ > #include "qemu/error-report.h" > #include "qemu/guest-random.h" > #include "qemu/timer.h" > +#include "qapi/error.h" > #include "qapi/visitor.h" > #include "migration/vmstate.h" > #include "hw/qdev-properties.h" > @@ -641,6 +642,7 @@ static void trng_prop_fault_event_set(Object *obj, Visitor *v, > const char *name, void *opaque, > Error **errp) > { > + ERRP_GUARD(); > Property *prop = opaque; > uint32_t *events = object_field_prop_ptr(obj, prop); visit_type_uint32(v, name, events, errp); if (*errp) { return; } Please do this instead: diff --git a/hw/misc/xlnx-versal-trng.c b/hw/misc/xlnx-versal-trng.c index b8111b8b66..6495188dc7 100644 --- a/hw/misc/xlnx-versal-trng.c +++ b/hw/misc/xlnx-versal-trng.c @@ -644,8 +644,7 @@ static void trng_prop_fault_event_set(Object *obj, Visitor *v, Property *prop = opaque; uint32_t *events = object_field_prop_ptr(obj, prop); - visit_type_uint32(v, name, events, errp); - if (*errp) { + if (!visit_type_uint32(v, name, events, errp)) { return; }