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| author | akpm@osdl.org <akpm@osdl.org> | 2005-05-01 08:58:35 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-05-01 08:58:35 -0700 |
| commit | 119f657c72fc07d6fd28c61de59cfba1566970a9 (patch) | |
| tree | 33c8070aa904c4919cf244cdcd7c01e54589bb9e /mm/mmap.c | |
| parent | f021e9210185b46e41ec3a0e78ec1621e168eacb (diff) | |
| download | lwn-119f657c72fc07d6fd28c61de59cfba1566970a9.tar.gz lwn-119f657c72fc07d6fd28c61de59cfba1566970a9.zip | |
[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: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/mmap.c')
| -rw-r--r-- | mm/mmap.c | 24 |
1 files changed, 19 insertions, 5 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index 6ea204cc751e..1ec0f6e9c0d8 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -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; +} |