ACPI: tables: x86: Reserve memory occupied by ACPI tables
The following problem has been reported by George Kennedy: Since commit 7fef431b ("mm/page_alloc: place pages to tail in __free_pages_core()") the following use after free occurs intermittently when ACPI tables are accessed. BUG: KASAN: use-after-free in ibft_init+0x134/0xc49 Read of size 4 at addr ffff8880be453004 by task swapper/0/1 CPU: 3 PID: 1 Comm: swapper/0 Not tainted 5.12.0-rc1-7a7fd0de #1 Call Trace: dump_stack+0xf6/0x158 print_address_description.constprop.9+0x41/0x60 kasan_report.cold.14+0x7b/0xd4 __asan_report_load_n_noabort+0xf/0x20 ibft_init+0x134/0xc49 do_one_initcall+0xc4/0x3e0 kernel_init_freeable+0x5af/0x66b kernel_init+0x16/0x1d0 ret_from_fork+0x22/0x30 ACPI tables mapped via kmap() do not have their mapped pages reserved and the pages can be "stolen" by the buddy allocator. Apparently, on the affected system, the ACPI table in question is not located in "reserved" memory, like ACPI NVS or ACPI Data, that will not be used by the buddy allocator, so the memory occupied by that table has to be explicitly reserved to prevent the buddy allocator from using it. In order to address this problem, rearrange the initialization of the ACPI tables on x86 to locate the initial tables earlier and reserve the memory occupied by them. The other architectures using ACPI should not be affected by this change. Link: https://lore.kernel.org/linux-acpi/1614802160-29362-1-git-send-email-george.kennedy@oracle.com/ Reported-by:George Kennedy <george.kennedy@oracle.com> Tested-by:
George Kennedy <george.kennedy@oracle.com> Signed-off-by:
Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by:
Mike Rapoport <rppt@linux.ibm.com> Cc: 5.10+ <stable@vger.kernel.org> # 5.10+
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