common/wireaddr: Fix an out-of-bounds bug in the address parser #8325
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Changelog-Fixed: In `struct wireaddr`, the `addr` buffer is defined with a length of DNS_ADDRLEN (255). When parsing a valid DNS name that is exactly 255 bytes long, the subsequent attempt to append a `NULL` terminator overruns the buffer and triggers an out-of-bounds error under UBSan. Fix this by removing the line that appends `NULL`. This change is safe because the preceding call to: `memset(&addr->addr, 0, sizeof(addr->addr))` already zeroes the entire buffer.
4 tasks
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This bug was discovered through the new fuzz test in #8324. |
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Note that this bug is triggerable from outside |
morehouse
reviewed
Jun 7, 2025
common/test/run-wireaddr.c
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| @@ -287,6 +224,31 @@ int main(int argc, char *argv[]) | |||
| expect->u.unresolved.port = 1234; | |||
| assert(wireaddr_internal_eq(&addr, expect)); | |||
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| const char raw_input[] = | |||
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Should add a comment describing the test, and also the bug that was fixed.
common/test/run-wireaddr.c
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| const u8 *crashing_input = tal_dup_arr(tmpctx, u8, (const u8*) raw_input, sizeof(raw_input) - 1, 0); | ||
| size_t crashing_input_len = tal_bytelen(crashing_input); | ||
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| struct wireaddr_internal decoded_wa; | ||
| assert(fromwire_wireaddr_internal(&crashing_input, &crashing_input_len, &decoded_wa)); |
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Can we improve the test to check the expected decoded values, as with the above tests?
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Right, the readability could also use some improvements.
Add a test in `common/test/run-wireaddr.c` that reproduces the out-of-bounds error when the fix is not applied.
morehouse
approved these changes
Jun 11, 2025
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In
struct wireaddr, theaddrbuffer is defined with a length ofDNS_ADDRLEN(255). When parsing a valid DNS name that is exactly 255 bytes long, the subsequent attempt to append aNULLterminator overruns the buffer and triggers an out-of-bounds error under UBSan.Fix this bug and add a test to guard against it.
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CC: @morehouse