libkmod: Check child range in memory mapped index #167
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If value of "first" is negative, then a broken index can trigger a stack based buffer overflow, because child_count could become larger than INDEX_CHILDMAX. Signed-off-by: Tobias Stoeckmann <[email protected]>
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| @@ -689,7 +689,7 @@ static struct index_mm_node *index_mm_read_node(struct index_mm *idx, uint32_t o | |||
| first = read_char_mm(&p); | |||
| last = read_char_mm(&p); | |||
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| if (first > last) | |||
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makes sense, but then now we silently use a corrupted index - modprobe even returns success.
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Which is also true for first > last or out of memory conditions with failing memory allocations here.
If it's a subtle hint to add error checks of index_mm_read_node callers: Yes, we should do that. ;) Eventually we have to adjust the API though, because index_dump itself returns void.
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If value of "first" is negative, then a broken index can trigger a stack based buffer overflow, because child_count could become larger than INDEX_CHILDMAX. Signed-off-by: Tobias Stoeckmann <[email protected]> Link: #167 Signed-off-by: Lucas De Marchi <[email protected]>
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Applied, thanks. |
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If value of
firstis negative, then a broken index can trigger a stack based buffer overflow, becausechild_countcould become larger than INDEX_CHILDMAX.Proof of Concept:
On glibc based systems, you will most likely encounter a message like
Alternatively, compile with address sanitizer.