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[PATCH] RLIMIT_AS checking fix

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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: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
akpm@osdl.org 2005-05-01 08:58:35 -07:00 committed by Linus Torvalds
parent f021e92101
commit 119f657c72
3 changed files with 23 additions and 8 deletions
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1
include/linux/mm.h
View File

@ -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);

24
mm/mmap.c
View File

@ -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;
}

6
mm/mremap.c
View File

@ -347,10 +347,10 @@ unsigned long do_mremap(unsigned long addr,
if (locked > lock_limit && !capable(CAP_IPC_LOCK))
goto out;
}
ret = -ENOMEM;
if ((current->mm->total_vm << PAGE_SHIFT) + (new_len - old_len)
> current->signal->rlim[RLIMIT_AS].rlim_cur)
if (!may_expand_vm(current->mm, (new_len - old_len) >> PAGE_SHIFT)) {
ret = -ENOMEM;
goto out;
}
if (vma->vm_flags & VM_ACCOUNT) {
charged = (new_len - old_len) >> PAGE_SHIFT;