fix(link-map): guard head conversion from memory to avoid overflow panic#2808
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jrootcache wants to merge 1 commit into0xMiden:nextfrom
Closed
fix(link-map): guard head conversion from memory to avoid overflow panic#2808jrootcache wants to merge 1 commit into0xMiden:nextfrom
jrootcache wants to merge 1 commit into0xMiden:nextfrom
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bobbinth
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Apr 26, 2026
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bobbinth
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bobbinth
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Thank you - but I don't think this change is actually a good idea.
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| // Be tolerant to potential malformed pointers: return None instead of panicking | ||
| // if the value cannot fit into a u32. | ||
| u32::try_from(head_ptr.as_canonical_u64()).ok() |
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If the pointer is malformed, it would mean that there is a serious bug in the transaction kernel and we should definitely either panic or return an error. So, returning None is probably not a good idea.
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Problem
There is a potential panic in LinkMap::head() when the memory-stored head pointer cannot be converted to a u32 (e.g., due to memory corruption or an out-of-range value).
Fix
Make the conversion fallible-safe by replacing the unwrap/expect with .ok(), returning None when the pointer cannot be represented as u32. This prevents panics on edge cases and keeps behavior stable for malformed data.
Why this is safe
The head() method already treats invalid/missing head pointers as None. Using .ok() preserves the existing contract (None for invalid head) and avoids panics in rare edge cases without altering normal operation.