Messages in this thread Patch in this message | | | Date | Sun, 28 Nov 2004 11:01:26 +0000 (GMT) | From | Hugh Dickins <> | Subject | [PATCH 1/2] VmLib wrapped: executable brk |
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In some cases /proc/<pid>/status shows VmLib: 42949..... kB.
If READ_IMPLIES_EXEC then the break area is VM_EXEC, but omitted from exec_vm since do_brk contains no __vm_stat_account call. Later munmaps count its pages out of exec_vm, hence (exec_vm - VmExe) can go negative.
do_brk is right not to call __vm_stat_account, its pages shouldn't need to be counted. What's wrong is that __vm_stat_account is counting all the VM_EXEC pages, whereas (to mimic 2.4 and earlier 2.6) it should be leaving VM_WRITE areas and non-vm_file areas out of exec_vm.
VmLib may still appear larger than before - where a READ_IMPLIES_EXEC personality makes what was a readonly mapping of a file now executable e.g. /usr/lib/locale stuff. And a program which mprotects its own text as writable will appear with wrapped VmLib: sorry, but while it's worth showing ordinary programs as ordinary, it's not worth much effort to avoid showing odd ones as odd.
Signed-off-by: Hugh Dickins <hugh@veritas.com> Acked-by: William Lee Irwin III <wli@holomorphy.com>
--- 2.6.10-rc2-bk9/mm/mmap.c 2004-11-15 16:21:24.000000000 +0000 +++ linux/mm/mmap.c 2004-11-25 15:58:55.710366040 +0000 @@ -744,12 +744,12 @@ void __vm_stat_account(struct mm_struct } #endif /* CONFIG_HUGETLB */ - if (file) + if (file) { mm->shared_vm += pages; - else if (flags & stack_flags) + if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC) + mm->exec_vm += pages; + } else if (flags & stack_flags) mm->stack_vm += pages; - if (flags & VM_EXEC) - mm->exec_vm += pages; if (flags & (VM_RESERVED|VM_IO)) mm->reserved_vm += pages; }
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