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 for kexec@lists.infradead.org; Thu, 11 Apr 2019 08:37:47 +0000
Date: Thu, 11 Apr 2019 10:37:38 +0200
From: Borislav Petkov <bp@alien8.de>
Subject: Re: [PATCH v4] x86/boot: Use efi_setup_data for searching RSDP on
 kexec-ed kernel
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References: <20190408231011.GA5402@jeru.linux.bs1.fc.nec.co.jp>
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To: Junichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Chao Fan <fanc.fnst@cn.fujitsu.com>, Kairui Song <kasong@redhat.com>, Baoquan He <bhe@redhat.com>, "x86@kernel.org" <x86@kernel.org>, "kexec@lists.infradead.org" <kexec@lists.infradead.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Dave Young <dyoung@redhat.com>

On Thu, Apr 11, 2019 at 08:16:45AM +0000, Junichi Nomura wrote:
> kexec_get_rsdp_addr() might fail on kexec-booted kernel, e.g. if the
> setup_data was invalid. In such a case, falling back to efi_get_rsdp_addr()
> will hit the problem of accessing invalid table pointer again.

Then you need to do this:

	if (kexeced kernel) {
		addr = kexec_get_rsdp_addr();
		if (!addr) {
			/* cannot get address */
			return -1;
		}

		return addr;
	}

and the calling function get_rsdp_addr() must check the return value and
if it is not 0, return immediately.

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

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