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Improved safety for user memory accesses.

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* Changed IS_USER_ADDRESS to check an address using USER_BASE and
  USER_SIZE, rather than just !IS_KERNEL_ADDRESS. The old check would
  allow user buffers to point into the physical memory map area.
* Added an unmapped hole at the end of the bottom half of the address
  space which catches buffers that cross into the uncanonical address
  region. This also removes the need to check for uncanonical return
  addresses in the syscall handler, it is no longer possible for the
  return address to be uncanonical under normal circumstances. All
  cases in which the return address might be changed by the kernel
  are still handled via the IRET path.
This commit is contained in:
Alex Smith
2012-08-02 09:32:33 +01:00
parent b77772725c
commit d93ed09564
7 changed files with 25 additions and 28 deletions
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headers/private/kernel/arch/ppc/arch_kernel.h
+2 -2
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@@ -23,10 +23,10 @@
#define USER_BASE 0x100000
#define USER_BASE_ANY USER_BASE
#define USER_SIZE (0x80000000 - (0x10000 + 0x100000))
#define USER_TOP (USER_BASE + USER_SIZE)
#define USER_TOP (USER_BASE + (USER_SIZE - 1))
#define KERNEL_USER_DATA_BASE 0x6fff0000
#define USER_STACK_REGION 0x70000000
#define USER_STACK_REGION_SIZE (USER_TOP - USER_STACK_REGION)
#define USER_STACK_REGION_SIZE ((USER_TOP - USER_STACK_REGION) + 1)
#endif /* _KERNEL_ARCH_PPC_KERNEL_H */