Commit 8c509665 authored by ZhangPeng's avatar ZhangPeng Committed by Ma Wupeng
Browse files

userswap: split uswap_register() to validate address ranges 

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6CAIM



--------------------------------

Split uswap_register() into uswap_register() and uswap_adjust_uffd_range().
Before validate_range(), use uswap_register() to handle uswap mode.
After validate_range(), use uswap_adjust_uffd_range() to change address
range to VMA range, which could reduce fragmentation caused by VMA
splitting.
By splitting uswap_register(), we could prevent the userswap registration
of invalid input address ranges.

Signed-off-by: default avatarZhangPeng <zhangpeng362@huawei.com>
parent 2e04865a

fs/userfaultfd.c

+12 −2
Original line number Diff line number Diff line
@@ -1282,6 +1282,9 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, 
	bool found;

	bool basic_ioctls;

	unsigned long start, end, vma_end;

#ifdef CONFIG_USERSWAP

	bool uswap_mode = false;

#endif



	user_uffdio_register = (struct uffdio_register __user *) arg;
@@ -1295,7 +1298,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, 
		goto out;

	vm_flags = 0;

#ifdef CONFIG_USERSWAP

	if (!uswap_register(&uffdio_register, &vm_flags, mm))

	if (!uswap_register(&uffdio_register, &uswap_mode))

		goto out;

#endif

	if (uffdio_register.mode & ~(UFFDIO_REGISTER_MODE_MISSING|
@@ -1310,7 +1313,14 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, 
			     uffdio_register.range.len);

	if (ret)

		goto out;



#ifdef CONFIG_USERSWAP

	if (uswap_mode)

		if (!uswap_adjust_uffd_range(&uffdio_register, &vm_flags,

					     mm)) {

			ret = -EINVAL;

			goto out;

		}

#endif

	start = uffdio_register.range.start;

	end = start + uffdio_register.range.len;

include/linux/userswap.h

+4 −2
Original line number Diff line number Diff line
@@ -28,7 +28,9 @@ int mfill_atomic_pte_nocopy(struct mm_struct *dst_mm, 
unsigned long uswap_mremap(unsigned long old_addr, unsigned long old_len,

			   unsigned long new_addr, unsigned long new_len);



bool uswap_register(struct uffdio_register *uffdio_register,

bool uswap_register(struct uffdio_register *uffdio_register, bool *uswap_mode);



bool uswap_adjust_uffd_range(struct uffdio_register *uffdio_register,

			     unsigned long *vm_flags, struct mm_struct *mm);



bool do_uswap_page(swp_entry_t entry, struct vm_fault *vmf,

mm/userswap.c

+17 −9
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 
#include <linux/mmu_notifier.h>

#include <linux/userswap.h>

#include <linux/userfaultfd_k.h>

#include <linux/security.h>



#include "internal.h"
@@ -462,11 +463,24 @@ int mfill_atomic_pte_nocopy(struct mm_struct *mm, 
	return ret;

}



bool uswap_register(struct uffdio_register *uffdio_register, bool *uswap_mode)

{

	if (!static_branch_unlikely(&userswap_enabled))

		return true;

	if (!(uffdio_register->mode & UFFDIO_REGISTER_MODE_USWAP))

		return true;

	uffdio_register->mode &= ~UFFDIO_REGISTER_MODE_USWAP;

	if (!uffdio_register->mode)

		return false;

	*uswap_mode = true;

	return true;

}



/*

 * register the whole vma overlapping with the address range to avoid splitting

 * the vma.

 * the vma which could reduce fragmentation.

 */

bool uswap_register(struct uffdio_register *uffdio_register,

bool uswap_adjust_uffd_range(struct uffdio_register *uffdio_register,

			     unsigned long *vm_flags, struct mm_struct *mm)

{

	struct vm_area_struct *vma;
@@ -474,12 +488,6 @@ bool uswap_register(struct uffdio_register *uffdio_register, 


	if (!static_branch_unlikely(&userswap_enabled))

		return true;

	if (!(uffdio_register->mode & UFFDIO_REGISTER_MODE_USWAP))

		return true;

	uffdio_register->mode &= ~UFFDIO_REGISTER_MODE_USWAP;

	if (!uffdio_register->mode)

		return false;



	end = uffdio_register->range.start + uffdio_register->range.len - 1;

	vma = find_vma(mm, uffdio_register->range.start);

	if (!vma)