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A couple hardened usercopy changes:

Browse source 
- drop now unneeded is_vmalloc_or_module() check; Laura Abbott
 - use enum instead of literals for stack frame API; Sahara
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 Version: GnuPG v1
 Comment: Kees Cook <kees@outflux.net>
 
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Merge tag 'usercopy-v4.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull hardened usercopy updates from Kees Cook:
 "A couple hardened usercopy changes:

   - drop now unneeded is_vmalloc_or_module() check (Laura Abbott)

   - use enum instead of literals for stack frame API (Sahara)"

* tag 'usercopy-v4.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  mm/usercopy: Drop extra is_vmalloc_or_module() check
  usercopy: Move enum for arch_within_stack_frames()
This commit is contained in:
Linus Torvalds 2017-05-02 10:45:15 -07:00
commit 5958cc49ed
3 changed files with 20 additions and 24 deletions
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13
arch/x86/include/asm/thread_info.h
View file

@ -170,9 +170,9 @@ static inline unsigned long current_stack_pointer(void)
* entirely contained by a single stack frame.
*
* Returns:
* 1 if within a frame
* -1 if placed across a frame boundary (or outside stack)
* 0 unable to determine (no frame pointers, etc)
* GOOD_FRAME if within a frame
* BAD_STACK if placed across a frame boundary (or outside stack)
* NOT_STACK unable to determine (no frame pointers, etc)
*/
static inline int arch_within_stack_frames(const void * const stack,
const void * const stackend,
@ -199,13 +199,14 @@ static inline int arch_within_stack_frames(const void * const stack,
* the copy as invalid.
*/
if (obj + len <= frame)
return obj >= oldframe + 2 * sizeof(void *) ? 1 : -1;
return obj >= oldframe + 2 * sizeof(void *) ?
GOOD_FRAME : BAD_STACK;
oldframe = frame;
frame = *(const void * const *)frame;
}
return -1;
return BAD_STACK;
#else
return 0;
return NOT_STACK;
#endif
}

12
include/linux/thread_info.h
View file

@ -22,6 +22,18 @@
#endif
#include <linux/bitops.h>
/*
* For per-arch arch_within_stack_frames() implementations, defined in
* asm/thread_info.h.
*/
enum {
BAD_STACK = -1,
NOT_STACK = 0,
GOOD_FRAME,
GOOD_STACK,
};
#include <asm/thread_info.h>
#ifdef __KERNEL__

19
mm/usercopy.c
View file

@ -19,15 +19,9 @@
#include <linux/sched.h>
#include <linux/sched/task.h>
#include <linux/sched/task_stack.h>
#include <linux/thread_info.h>
#include <asm/sections.h>
enum {
BAD_STACK = -1,
NOT_STACK = 0,
GOOD_FRAME,
GOOD_STACK,
};
/*
* Checks if a given pointer and length is contained by the current
* stack frame (if possible).
@ -206,17 +200,6 @@ static inline const char *check_heap_object(const void *ptr, unsigned long n,
{
struct page *page;
/*
* Some architectures (arm64) return true for virt_addr_valid() on
* vmalloced addresses. Work around this by checking for vmalloc
* first.
*
* We also need to check for module addresses explicitly since we
* may copy static data from modules to userspace
*/
if (is_vmalloc_or_module_addr(ptr))
return NULL;
if (!virt_addr_valid(ptr))
return NULL;