Commit 119f657c authored by akpm@osdl.org's avatar akpm@osdl.org Committed by Linus Torvalds
Browse files

[PATCH] RLIMIT_AS checking fix 



Address bug #4508: there's potential for wraparound in the various places
where we perform RLIMIT_AS checking.

(I'm a bit worried about acct_stack_growth().  Are we sure that vma->vm_mm is
always equal to current->mm?  If not, then we're comparing some other
process's total_vm with the calling process's rlimits).

Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent f021e921

include/linux/mm.h

+1 −0
Original line number Diff line number Diff line
@@ -726,6 +726,7 @@ extern void __vma_link_rb(struct mm_struct *, struct vm_area_struct *, 
extern struct vm_area_struct *copy_vma(struct vm_area_struct **,

	unsigned long addr, unsigned long len, pgoff_t pgoff);

extern void exit_mmap(struct mm_struct *);

extern int may_expand_vm(struct mm_struct *mm, unsigned long npages);



extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);

mm/mmap.c

+19 −5
Original line number Diff line number Diff line
@@ -1009,8 +1009,7 @@ munmap_back: 
	}



	/* Check against address space limit. */

	if ((mm->total_vm << PAGE_SHIFT) + len

	    > current->signal->rlim[RLIMIT_AS].rlim_cur)

	if (!may_expand_vm(mm, len >> PAGE_SHIFT))

		return -ENOMEM;



	if (accountable && (!(flags & MAP_NORESERVE) ||
@@ -1421,7 +1420,7 @@ static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, un 
	struct rlimit *rlim = current->signal->rlim;



	/* address space limit tests */

	if (mm->total_vm + grow > rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT)

	if (!may_expand_vm(mm, grow))

		return -ENOMEM;



	/* Stack limit test */
@@ -1848,8 +1847,7 @@ unsigned long do_brk(unsigned long addr, unsigned long len) 
	}



	/* Check against address space limits *after* clearing old maps... */

	if ((mm->total_vm << PAGE_SHIFT) + len

	    > current->signal->rlim[RLIMIT_AS].rlim_cur)

	if (!may_expand_vm(mm, len >> PAGE_SHIFT))

		return -ENOMEM;



	if (mm->map_count > sysctl_max_map_count)
@@ -2019,3 +2017,19 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, 
	}

	return new_vma;

}



/*

 * Return true if the calling process may expand its vm space by the passed

 * number of pages

 */

int may_expand_vm(struct mm_struct *mm, unsigned long npages)

{

	unsigned long cur = mm->total_vm;	/* pages */

	unsigned long lim;



	lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;



	if (cur + npages > lim)

		return 0;

	return 1;

}

mm/mremap.c

+3 −3
Original line number Diff line number Diff line
@@ -347,10 +347,10 @@ unsigned long do_mremap(unsigned long addr, 
		if (locked > lock_limit && !capable(CAP_IPC_LOCK))

			goto out;

	}

	if (!may_expand_vm(current->mm, (new_len - old_len) >> PAGE_SHIFT)) {

		ret = -ENOMEM;

	if ((current->mm->total_vm << PAGE_SHIFT) + (new_len - old_len)

	    > current->signal->rlim[RLIMIT_AS].rlim_cur)

		goto out;

	}



	if (vma->vm_flags & VM_ACCOUNT) {

		charged = (new_len - old_len) >> PAGE_SHIFT;

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