linux_dsm_epyc7002/arch/arm64/mm
Ard Biesheuvel 1151f838cb arm64: kernel: restrict /dev/mem read() calls to linear region
When running lscpu on an AArch64 system that has SMBIOS version 2.0
tables, it will segfault in the following way:

  Unable to handle kernel paging request at virtual address ffff8000bfff0000
  pgd = ffff8000f9615000
  [ffff8000bfff0000] *pgd=0000000000000000
  Internal error: Oops: 96000007 [#1] PREEMPT SMP
  Modules linked in:
  CPU: 0 PID: 1284 Comm: lscpu Not tainted 4.11.0-rc3+ #103
  Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015
  task: ffff8000fa78e800 task.stack: ffff8000f9780000
  PC is at __arch_copy_to_user+0x90/0x220
  LR is at read_mem+0xcc/0x140

This is caused by the fact that lspci issues a read() on /dev/mem at the
offset where it expects to find the SMBIOS structure array. However, this
region is classified as EFI_RUNTIME_SERVICE_DATA (as per the UEFI spec),
and so it is omitted from the linear mapping.

So let's restrict /dev/mem read/write access to those areas that are
covered by the linear region.

Reported-by: Alexander Graf <agraf@suse.de>
Fixes: 4dffbfc48d ("arm64/efi: mark UEFI reserved regions as MEMBLOCK_NOMAP")
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-06-01 18:26:26 +01:00
..
cache.S arm64: don't pull uaccess.h into *.S 2016-12-26 13:05:17 -05:00
context.c arm64: cache: Remove support for ASID-tagged VIVT I-caches 2017-03-20 16:16:57 +00:00
copypage.c arm64: Defer dcache flush in __cpu_copy_user_page 2015-12-17 11:07:13 +00:00
dma-mapping.c IOMMU Updates for Linux v4.12 2017-05-09 15:15:47 -07:00
dump.c arm64: dump: Add checking for writable and exectuable pages 2016-11-07 18:15:04 +00:00
extable.c arm64: migrate exception table users off module.h and onto extable.h 2016-09-20 09:36:21 +01:00
fault.c arm64: Call __show_regs directly 2017-05-30 11:07:41 +01:00
flush.c arm64: cache: Merge cachetype.h into cache.h 2017-03-20 16:16:59 +00:00
hugetlbpage.c Revert "Revert "arm64: hugetlb: partial revert of 66b3923a1a0f"" 2017-04-07 12:27:29 +01:00
init.c arm64: kdump: provide /proc/vmcore file 2017-04-05 18:31:38 +01:00
ioremap.c arm64: use is_vmalloc_addr 2017-02-09 13:47:56 +00:00
kasan_init.c arm64: kasan: avoid bad virt_to_pfn() 2017-03-10 17:41:41 +00:00
Makefile arm64: Add support for CONFIG_DEBUG_VIRTUAL 2017-01-12 15:05:39 +00:00
mmap.c arm64: kernel: restrict /dev/mem read() calls to linear region 2017-06-01 18:26:26 +01:00
mmu.c arm64: mm: explicity include linux/vmalloc.h 2017-05-30 11:07:42 +01:00
numa.c ACPI/NUMA: Do not map pxm to node when NUMA is turned off 2016-12-15 11:32:32 +01:00
pageattr.c arm64: use set_memory.h header 2017-05-08 17:15:13 -07:00
pgd.c arm64: mm: drop fixup_init() and mm.h 2016-09-06 19:09:38 +01:00
physaddr.c arm64: Add support for CONFIG_DEBUG_VIRTUAL 2017-01-12 15:05:39 +00:00
proc.S arm64: Avoid clobbering mm in erratum workaround on QDF2400 2017-02-24 10:55:31 +00:00
ptdump_debugfs.c arm64: dump: Make ptdump debugfs a separate option 2016-11-07 18:15:04 +00:00