Use constant-time comparison for OMAPI authentication signature#8
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kodareef5 wants to merge 2 commits intoisc-projects:masterfrom
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Use constant-time comparison for OMAPI authentication signature#8kodareef5 wants to merge 2 commits intoisc-projects:masterfrom
kodareef5 wants to merge 2 commits intoisc-projects:masterfrom
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1. common/tree.c: Change new_len from signed int to unsigned int and add UINT_MAX/2 check before doubling. Signed int overflow in the doubling loop is undefined behavior that could cause infinite loop. 2. common/parse.c: Check universe_max > INT_MAX/2 before doubling the option space array. 3. omapip/alloc.c: Check count * sizeof(omapi_addr_t) + sizeof(list) does not overflow size_t before allocation. 4. omapip/array.c: Check (max + delta) * sizeof(char *) does not overflow size_t before array growth allocation. 5. common/options.c:3664: Check length * 4 + 3 does not overflow unsigned int in FQDN option buffer allocation. 6. common/options.c:2738: Check num_opts * 2 does not overflow int in server ORO buffer allocation.
The OMAPI protocol verifies HMAC-MD5 authentication signatures using memcmp(), which returns early on the first byte mismatch. This leaks timing information about how many bytes of the signature are correct, enabling a timing side-channel attack against the OMAPI management interface. Replace with a constant-time XOR accumulation loop that examines all bytes regardless of match position.
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omapip/protocol.cline 716 verifies OMAPI HMAC-MD5 authentication signatures usingmemcmp(), which returns early on the first byte mismatch. This leaks timing information about how many bytes of the signature are correct.Replace with a constant-time XOR accumulation loop that examines all bytes regardless of match position. The
volatilequalifier prevents compiler optimization from reintroducing early exit.Builds clean with
-Wall -Werror.