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Date:   Thu, 11 Apr 2019 10:37:38 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     Junichi Nomura <j-nomura@ce.jp.nec.com>
Cc:     Dave Young <dyoung@redhat.com>,
        Chao Fan <fanc.fnst@cn.fujitsu.com>,
        Baoquan He <bhe@redhat.com>, Kairui Song <kasong@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>
Subject: Re: [PATCH v4] x86/boot: Use efi_setup_data for searching RSDP on
 kexec-ed kernel
Message-ID: <20190411083738.GC30080@zn.tnic>
References: <20190408231011.GA5402@jeru.linux.bs1.fc.nec.co.jp>
 <20190410171431.GE26580@zn.tnic>
 <7cbc096d-0548-18b1-a335-8ba114f234a7@ce.jp.nec.com>
 <20190411080927.GA30080@zn.tnic>
 <e4de0520-ade8-2834-dadf-7af68701356b@ce.jp.nec.com>
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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.

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