forked from Minki/linux
[PATCH] prevent NULL mmap in topdown model
Prevent the topdown allocator from allocating mmap areas all the way down to address zero. We still allow a MAP_FIXED mapping of page 0 (needed for various things, ranging from Wine and DOSEMU to people who want to allow speculative loads off a NULL pointer). Tested by Chris Wright. Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -1244,7 +1244,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
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addr = mm->free_area_cache;
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/* make sure it can fit in the remaining address space */
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if (addr >= len) {
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if (addr > len) {
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vma = find_vma(mm, addr-len);
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if (!vma || addr <= vma->vm_start)
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/* remember the address as a hint for next time */
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@ -1266,7 +1266,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
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/* try just below the current vma->vm_start */
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addr = vma->vm_start-len;
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} while (len <= vma->vm_start);
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} while (len < vma->vm_start);
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/*
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* A failed mmap() very likely causes application failure,
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