diff options
| author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2017-05-19 16:42:00 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@google.com> | 2020-11-15 15:31:22 +0000 |
| commit | f9eabbd3d21b9bd1eae5a86b14cb7072dad63f82 (patch) | |
| tree | f1a14bfa1fb8130fbab758aab6570c52449b2b65 | |
| parent | 2db1fabeccc1151c48a9b2d075b3985f74e7c0cf (diff) | |
UPSTREAM: 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: 4dffbfc48d65 ("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>
(cherry picked from commit 1151f838cb626005f4d69bf675dacaaa5ea909d6)
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I89d897b56819b50efbd5f3b08cf542b33190e4f1
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
| -rw-r--r-- | arch/arm64/mm/mmap.c | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c index 232f787a088a..2d705ab815e4 100644 --- a/arch/arm64/mm/mmap.c +++ b/arch/arm64/mm/mmap.c @@ -18,6 +18,7 @@ #include <linux/elf.h> #include <linux/fs.h> +#include <linux/memblock.h> #include <linux/mm.h> #include <linux/mman.h> #include <linux/export.h> @@ -104,12 +105,18 @@ EXPORT_SYMBOL_GPL(arch_pick_mmap_layout); */ int valid_phys_addr_range(phys_addr_t addr, size_t size) { - if (addr < PHYS_OFFSET) - return 0; - if (addr + size > __pa(high_memory - 1) + 1) - return 0; - - return 1; + /* + * Check whether addr is covered by a memory region without the + * MEMBLOCK_NOMAP attribute, and whether that region covers the + * entire range. In theory, this could lead to false negatives + * if the range is covered by distinct but adjacent memory regions + * that only differ in other attributes. However, few of such + * attributes have been defined, and it is debatable whether it + * follows that /dev/mem read() calls should be able traverse + * such boundaries. + */ + return memblock_is_region_memory(addr, size) && + memblock_is_map_memory(addr); } /* |