[0/4] Assorted improvements to usercopy

Message

Matthew Wilcox Jan. 10, 2022, 11:15 p.m. UTC

The HARDENED_USERCOPY_PAGESPAN config option is hard to turn on because
much of the kernel uses non-compound high-order page allocations.
This patchset extracts the valuable parts of HARDENED_USERCOPY_PAGESPAN
and then removes the remainder.

v5:
 - Use get_vm_area_size() instead of ->size directly (Mark Hemment)
 - Rebase to current Linus (the slab merge changed a lot of code)
v4:
 - Add the fourth patch to remove HARDENED_USERCOPY_PAGESPAN
v3:
 - Remove a now-unused variable
v2:
 - Prevent a NULL pointer dereference when a vmalloc-range pointer
   doesn't have an associated allocation (me)
 - Report better offsets than "0" (Kees)

Matthew Wilcox (Oracle) (4):
  mm/usercopy: Check kmap addresses properly
  mm/usercopy: Detect vmalloc overruns
  mm/usercopy: Detect large folio overruns
  usercopy: Remove HARDENED_USERCOPY_PAGESPAN

 arch/x86/include/asm/highmem.h   |  1 +
 include/linux/highmem-internal.h | 10 ++++
 mm/usercopy.c                    | 97 +++++++++-----------------------
 security/Kconfig                 | 13 +----
 4 files changed, 39 insertions(+), 82 deletions(-)