mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-29 23:53:55 +08:00
1869305009
The vm_populate() code populates user mappings without constantly holding the mmap_sem. This makes it susceptible to racy userspace programs: the user mappings may change while vm_populate() is running, and in this case vm_populate() may end up populating the new mapping instead of the old one. In order to reduce the possibility of userspace getting surprised by this behavior, this change introduces the VM_POPULATE vma flag which gets set on vmas we want vm_populate() to work on. This way vm_populate() may still end up populating the new mapping after such a race, but only if the new mapping is also one that the user has requested (using MAP_SHARED, MAP_LOCKED or mlock) to be populated. Signed-off-by: Michel Lespinasse <walken@google.com> Acked-by: Rik van Riel <riel@redhat.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Cc: Greg Ungerer <gregungerer@westnet.com.au> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
87 lines
2.1 KiB
C
87 lines
2.1 KiB
C
#ifndef _LINUX_MMAN_H
|
|
#define _LINUX_MMAN_H
|
|
|
|
#include <linux/mm.h>
|
|
#include <linux/percpu_counter.h>
|
|
|
|
#include <linux/atomic.h>
|
|
#include <uapi/linux/mman.h>
|
|
|
|
extern int sysctl_overcommit_memory;
|
|
extern int sysctl_overcommit_ratio;
|
|
extern struct percpu_counter vm_committed_as;
|
|
|
|
unsigned long vm_memory_committed(void);
|
|
|
|
static inline void vm_acct_memory(long pages)
|
|
{
|
|
percpu_counter_add(&vm_committed_as, pages);
|
|
}
|
|
|
|
static inline void vm_unacct_memory(long pages)
|
|
{
|
|
vm_acct_memory(-pages);
|
|
}
|
|
|
|
/*
|
|
* Allow architectures to handle additional protection bits
|
|
*/
|
|
|
|
#ifndef arch_calc_vm_prot_bits
|
|
#define arch_calc_vm_prot_bits(prot) 0
|
|
#endif
|
|
|
|
#ifndef arch_vm_get_page_prot
|
|
#define arch_vm_get_page_prot(vm_flags) __pgprot(0)
|
|
#endif
|
|
|
|
#ifndef arch_validate_prot
|
|
/*
|
|
* This is called from mprotect(). PROT_GROWSDOWN and PROT_GROWSUP have
|
|
* already been masked out.
|
|
*
|
|
* Returns true if the prot flags are valid
|
|
*/
|
|
static inline int arch_validate_prot(unsigned long prot)
|
|
{
|
|
return (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM)) == 0;
|
|
}
|
|
#define arch_validate_prot arch_validate_prot
|
|
#endif
|
|
|
|
/*
|
|
* Optimisation macro. It is equivalent to:
|
|
* (x & bit1) ? bit2 : 0
|
|
* but this version is faster.
|
|
* ("bit1" and "bit2" must be single bits)
|
|
*/
|
|
#define _calc_vm_trans(x, bit1, bit2) \
|
|
((bit1) <= (bit2) ? ((x) & (bit1)) * ((bit2) / (bit1)) \
|
|
: ((x) & (bit1)) / ((bit1) / (bit2)))
|
|
|
|
/*
|
|
* Combine the mmap "prot" argument into "vm_flags" used internally.
|
|
*/
|
|
static inline unsigned long
|
|
calc_vm_prot_bits(unsigned long prot)
|
|
{
|
|
return _calc_vm_trans(prot, PROT_READ, VM_READ ) |
|
|
_calc_vm_trans(prot, PROT_WRITE, VM_WRITE) |
|
|
_calc_vm_trans(prot, PROT_EXEC, VM_EXEC) |
|
|
arch_calc_vm_prot_bits(prot);
|
|
}
|
|
|
|
/*
|
|
* Combine the mmap "flags" argument into "vm_flags" used internally.
|
|
*/
|
|
static inline unsigned long
|
|
calc_vm_flag_bits(unsigned long flags)
|
|
{
|
|
return _calc_vm_trans(flags, MAP_GROWSDOWN, VM_GROWSDOWN ) |
|
|
_calc_vm_trans(flags, MAP_DENYWRITE, VM_DENYWRITE ) |
|
|
((flags & MAP_LOCKED) ? (VM_LOCKED | VM_POPULATE) : 0) |
|
|
(((flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE) ?
|
|
VM_POPULATE : 0);
|
|
}
|
|
#endif /* _LINUX_MMAN_H */
|