uprobes: Restrict valid_vma(false) to skip VM_SHARED vmas
valid_vma(false) ignores ->vm_flags, this is not actually right. We should never try to write into MAP_SHARED mapping, this can confuse an apllication which actually writes to ->vm_file. With this patch valid_vma(false) ignores VM_WRITE only but checks other (immutable) bits checked by valid_vma(true). This can also speedup uprobe_munmap() and uprobe_unregister(). Note: even after this patch _unregister can confuse the probed application if it does mprotect(PROT_WRITE) after _register and installs "int3", but this is hardly possible to avoid and this doesn't differ from gdb case. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
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@ -100,17 +100,12 @@ struct uprobe {
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*/
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static bool valid_vma(struct vm_area_struct *vma, bool is_register)
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{
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if (!vma->vm_file)
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return false;
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vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_SHARED;
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if (!is_register)
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return true;
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if (is_register)
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flags |= VM_WRITE;
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if ((vma->vm_flags & (VM_HUGETLB | VM_WRITE | VM_MAYEXEC | VM_SHARED))
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== VM_MAYEXEC)
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return true;
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return false;
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return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC;
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}
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static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset)
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