Re: [PATCH 0/2] mm: make copy_to_kernel_nofault() not fault on user addresses

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Le 02/09/2024 à 07:31, Omar Sandoval a écrit :
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From: Omar Sandoval <osandov@xxxxxx>

Hi,

I hit a case where copy_to_kernel_nofault() will fault (lol): if the
destination address is in userspace and x86 Supervisor Mode Access
Prevention is enabled. Patch 2 has the details and the fix. Patch 1
renames a helper function so that its use in patch 2 makes more sense.
If the rename is too intrusive, I can drop it.

The name of the function is "copy_to_kernel". If the destination is a user address, it is not a copy to kernel but a copy to user and you already have the function copy_to_user() for that. copy_to_user() properly handles SMAP.

Christophe



Thanks,
Omar

Omar Sandoval (2):
   mm: rename copy_from_kernel_nofault_allowed() to
     copy_kernel_nofault_allowed()
   mm: make copy_to_kernel_nofault() not fault on user addresses

  arch/arm/mm/fault.c         |  2 +-
  arch/loongarch/mm/maccess.c |  2 +-
  arch/mips/mm/maccess.c      |  2 +-
  arch/parisc/lib/memcpy.c    |  2 +-
  arch/powerpc/mm/maccess.c   |  2 +-
  arch/um/kernel/maccess.c    |  2 +-
  arch/x86/mm/maccess.c       |  4 ++--
  include/linux/uaccess.h     |  2 +-
  mm/maccess.c                | 10 ++++++----
  9 files changed, 15 insertions(+), 13 deletions(-)

--
2.46.0






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