90f546b2c1
Signed-off-by: Qiumiao Zhang <zhangqiumiao1@huawei.com> (cherry picked from commit e62f9657ab28a168cd5badeccf75370414ad34f5)
65 lines
2.3 KiB
Diff
65 lines
2.3 KiB
Diff
From 48f569c78a496d3e11a4605b0999bc34fa5bc977 Mon Sep 17 00:00:00 2001
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From: Michael Chang <mchang@suse.com>
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Date: Mon, 25 Sep 2023 13:58:18 +0800
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Subject: kern/acpi: Skip NULL entries in RSDT and XSDT
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During attempts to configure a serial console, a Page Fault Exception
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and system reset were encountered, specifically on release 2.12~rc1.
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This issue was not present in prior versions and seemed to affect only
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a specific machine, potentially pointing to hardware or firmware flaw.
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After investigation, it was discovered that the invalid page access
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occurred during the discovery of serial MMIO ports as specified by
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ACPI's SPCR table [1]. The recent change uncovered an issue in GRUB's
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ACPI driver.
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In certain cases, the XSDT/RSDT root table might contain a NULL entry as
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a terminator, depending on how the tables are assembled. GRUB cannot
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blindly trust the address in the root table to be valid and should
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perform a sanity check for NULL entries. This patch introduces this
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simple check.
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This fix is also inspired by a related Linux kernel fix [2].
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[1] 7b192ec4c term/ns8250: Use ACPI SPCR table when available to configure serial
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[2] 0f929fbf0 ACPICA: Tables: Add new mechanism to skip NULL entries in RSDT and XSDT.
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Reference:https://git.savannah.gnu.org/cgit/grub.git/commit/?id=48f569c78a496d3e11a4605b0999bc34fa5bc977
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Conflict:NA
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Signed-off-by: Michael Chang <mchang@suse.com>
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Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
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---
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grub-core/kern/acpi.c | 8 ++++++++
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1 file changed, 8 insertions(+)
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diff --git a/grub-core/kern/acpi.c b/grub-core/kern/acpi.c
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index c61115d..48ded4e 100644
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--- a/grub-core/kern/acpi.c
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+++ b/grub-core/kern/acpi.c
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@@ -51,6 +51,10 @@ grub_acpi_rsdt_find_table (struct grub_acpi_table_header *rsdt, const char *sig)
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for (; s; s--, ptr++)
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{
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struct grub_acpi_table_header *tbl;
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+
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+ /* Skip NULL entries in RSDT/XSDT. */
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+ if (!ptr->val)
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+ continue;
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tbl = (struct grub_acpi_table_header *) (grub_addr_t) ptr->val;
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if (grub_memcmp (tbl->signature, sig, 4) == 0)
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return tbl;
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@@ -75,6 +79,10 @@ grub_acpi_xsdt_find_table (struct grub_acpi_table_header *xsdt, const char *sig)
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for (; s; s--, ptr++)
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{
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struct grub_acpi_table_header *tbl;
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+
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+ /* Skip NULL entries in RSDT/XSDT. */
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+ if (!ptr->val)
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+ continue;
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#if GRUB_CPU_SIZEOF_VOID_P != 8
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if (ptr->val >> 32)
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continue;
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--
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cgit v1.1
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