From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5B34D73489 for ; Thu, 21 Dec 2023 13:14:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="R3ujxu66" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1703164483; 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=1eNoYJka76W6z/XIQNg+OgUP1x/5sVSGmIF7sB3PyIM=; b=R3ujxu667YT4xSxNx/5hAh4bvS1jjF+Rms+Qic0uAp50hR58AWkEQkvY5vVUXzsDPj+h1X mzblnrGzYWYFIkdbrptmtgy3uNBXR+d3fn7HDUnTYt8sxRQbbgRQTXBQsaDT6OXwdlDN+j tJCjqw7ihqjEj1s52fjur9KCC/EtTvo= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-454-9gOrF8nDO3O1s7WKoG1OmQ-1; Thu, 21 Dec 2023 08:14:39 -0500 X-MC-Unique: 9gOrF8nDO3O1s7WKoG1OmQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (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 8B5AD3816B4E; Thu, 21 Dec 2023 13:14:39 +0000 (UTC) Received: from localhost (unknown [10.72.116.38]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D7ACC2166B31; Thu, 21 Dec 2023 13:14:38 +0000 (UTC) Date: Thu, 21 Dec 2023 21:14:35 +0800 From: Baoquan He To: fuqiang wang Cc: Vivek Goyal , Dave Young , Yuntao Wang , kexec@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/2] x86/kexec: Fix potential out of bounds in crash_setup_memmap_entries() Message-ID: References: <20231220055733.100325-1-fuqiang.wang@easystack.cn> <20231220055733.100325-2-fuqiang.wang@easystack.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231220055733.100325-2-fuqiang.wang@easystack.cn> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.6 On 12/20/23 at 01:57pm, fuqiang wang wrote: > In memmap_exclude_ranges(), there will exclude elfheader from > crashk_res. In the current x86 architecture code, the elfheader is > always allocated at crashk_res.start. It seems that there won't be a > split a new range. But it depends on the allocation position of > elfheader in crashk_res. To avoid potential out of bounds in future, Set > the array size to 2. If so, I would suggest to add extra slot for low 1M too in fill_up_crash_elf_data() lest the low 1M could be changed in the future, e.g [start, 1M]. > > But similar issue will not exist in fill_up_crash_elf_data(). Because > the range to be excluded is [0, 1M], start (0) is special and will not > appear in the middle of existing cmem->ranges[]. I added a comment to > explain it. > > Signed-off-by: fuqiang wang > --- > arch/x86/kernel/crash.c | 20 ++++++++++++++------ > 1 file changed, 14 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c > index c92d88680dbf..1c15d0884c90 100644 > --- a/arch/x86/kernel/crash.c > +++ b/arch/x86/kernel/crash.c > @@ -149,6 +149,13 @@ static struct crash_mem *fill_up_crash_elf_data(void) > /* > * Exclusion of crash region and/or crashk_low_res may cause > * another range split. So add extra two slots here. > + * > + * Exclusion of low 1M may not cause another range split, because the > + * range of exclude is [0, 1M] and the condition for splitting a new > + * region is that the start, end parameters are both in a certain > + * existing region in cmem and cannot be equal to existing region's > + * start or end. Obviously, the start of [0, 1M] cannot meet this > + * condition. > */ > nr_ranges += 2; > cmem = vzalloc(struct_size(cmem, ranges, nr_ranges)); > @@ -282,9 +289,15 @@ int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params) > struct crash_memmap_data cmd; > struct crash_mem *cmem; > > - cmem = vzalloc(struct_size(cmem, ranges, 1)); > + cmem = vzalloc(struct_size(cmem, ranges, 2)); > if (!cmem) > return -ENOMEM; > + cmem->max_nr_ranges = 2; > + > + /* Exclude some ranges from crashk_res and add rest to memmap */ > + ret = memmap_exclude_ranges(image, cmem, crashk_res.start, crashk_res.end); > + if (ret) > + goto out; > > memset(&cmd, 0, sizeof(struct crash_memmap_data)); > cmd.params = params; > @@ -320,11 +333,6 @@ int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params) > add_e820_entry(params, &ei); > } > > - /* Exclude some ranges from crashk_res and add rest to memmap */ > - ret = memmap_exclude_ranges(image, cmem, crashk_res.start, crashk_res.end); > - if (ret) > - goto out; And you didn't mention moving above code block up in log. I would suggest keeping it as is because it looks more reasonable to be adjacent to the following cmem->ranges[] handling. > - > for (i = 0; i < cmem->nr_ranges; i++) { > ei.size = cmem->ranges[i].end - cmem->ranges[i].start + 1; > > -- > 2.42.0 >