[{"id":3682972,"web_url":"http://patchwork.ozlabs.org/comment/3682972/","msgid":"<9a8407d1-ce20-48a5-9975-4b08075e3768@linaro.org>","list_archive_url":null,"date":"2026-04-27T20:40:16","subject":"Re: [PATCH 08/41] hw/intc/apic: guard against NULL cpu in set_id","submitter":{"id":85046,"url":"http://patchwork.ozlabs.org/api/people/85046/","name":"Philippe Mathieu-Daudé","email":"philmd@linaro.org"},"content":"On 27/4/26 21:42, Marc-André Lureau wrote:\n> apic_common_set_id() dereferences s->cpu to check for x2APIC support\n> when the APIC ID is >= 255. On a standalone APIC object that has not\n> been attached to a CPU, s->cpu is NULL, causing a segfault.\n> \n> Add a NULL check before dereferencing. When there is no CPU, the\n> x2APIC feature cannot be verified, so reject the large APIC ID.\n> \n> Fixes: b5ee0468e9d2 (\"apic: add support for x2APIC mode\")\n> Signed-off-by: Marc-André Lureau \n> ---\n> hw/intc/apic_common.c | 2 +-\n> 1 file changed, 1 insertion(+), 1 deletion(-)\n> \n> diff --git a/hw/intc/apic_common.c b/hw/intc/apic_common.c\n> index bf4abc21d7b..874a05e529c 100644\n> --- a/hw/intc/apic_common.c\n> +++ b/hw/intc/apic_common.c\n> @@ -421,7 +421,7 @@ static void apic_common_set_id(Object *obj, Visitor *v, const char *name,\n> return;\n> }\n\nCould we check s->cpu earlier, i.e. on entry?\n\nOr actually, why don't we use a link property checked once\nin apic_common_realize()?\n\n> \n> - if (value >= 255 && !cpu_has_x2apic_feature(&s->cpu->env)) {\n> + if (value >= 255 && (!s->cpu || !cpu_has_x2apic_feature(&s->cpu->env))) {\n> error_setg(&local_err,\n> \"APIC ID %d requires x2APIC feature in CPU\",\n> value);\n>","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=linaro.org header.i=@linaro.org header.a=rsa-sha256\n header.s=google header.b=tjN7Qm3W;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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