WSL2-Linux-Kernel/Documentation/arm64
Catalin Marinas dcde237319 mm: Avoid creating virtual address aliases in brk()/mmap()/mremap()
Currently the arm64 kernel ignores the top address byte passed to brk(),
mmap() and mremap(). When the user is not aware of the 56-bit address
limit or relies on the kernel to return an error, untagging such
pointers has the potential to create address aliases in user-space.
Passing a tagged address to munmap(), madvise() is permitted since the
tagged pointer is expected to be inside an existing mapping.

The current behaviour breaks the existing glibc malloc() implementation
which relies on brk() with an address beyond 56-bit to be rejected by
the kernel.

Remove untagging in the above functions by partially reverting commit
ce18d171cb ("mm: untag user pointers in mmap/munmap/mremap/brk"). In
addition, update the arm64 tagged-address-abi.rst document accordingly.

Link: https://bugzilla.redhat.com/1797052
Fixes: ce18d171cb ("mm: untag user pointers in mmap/munmap/mremap/brk")
Cc: <stable@vger.kernel.org> # 5.4.x-
Cc: Florian Weimer <fweimer@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reported-by: Victor Stinner <vstinner@redhat.com>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
2020-02-20 10:03:14 +00:00
..
acpi_object_usage.rst docs: arm64: convert docs to ReST and rename to .rst 2019-06-14 14:20:27 -06:00
arm-acpi.rst docs: arm64: convert docs to ReST and rename to .rst 2019-06-14 14:20:27 -06:00
booting.rst arm64: Document ICC_CTLR_EL3.PMHE setting requirements 2019-10-15 12:26:15 +01:00
cpu-feature-registers.rst Merge branch 'for-next/rng' into for-next/core 2020-01-22 11:38:53 +00:00
elf_hwcaps.rst Merge branch 'for-next/rng' into for-next/core 2020-01-22 11:38:53 +00:00
hugetlbpage.rst docs: arm64: convert docs to ReST and rename to .rst 2019-06-14 14:20:27 -06:00
index.rst arm64: Add tagged-address-abi.rst to index.rst 2019-08-22 18:22:57 +01:00
kasan-offsets.sh arm64: kasan: Switch to using KASAN_SHADOW_OFFSET 2019-08-09 11:17:11 +01:00
legacy_instructions.rst docs: arm64: convert docs to ReST and rename to .rst 2019-06-14 14:20:27 -06:00
memory.rst docs: arm64: fix trivial spelling enought to enough in memory.rst 2020-02-20 10:03:14 +00:00
perf.txt arm64: docs: Document perf event attributes 2019-04-24 15:46:26 +01:00
pointer-authentication.rst docs: arm64: convert docs to ReST and rename to .rst 2019-06-14 14:20:27 -06:00
silicon-errata.rst arm64: Workaround for Cortex-A55 erratum 1530923 2020-01-16 10:44:14 +00:00
sve.rst It's been a relatively busy cycle for docs: 2019-07-09 12:34:26 -07:00
tagged-address-abi.rst mm: Avoid creating virtual address aliases in brk()/mmap()/mremap() 2020-02-20 10:03:14 +00:00
tagged-pointers.rst arm64: Relax Documentation/arm64/tagged-pointers.rst 2019-08-27 18:16:20 +01:00