Fix ospf checksum #20706 (backport #20729)#20841
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Jafaral merged 1 commit intostable/10.5from Feb 14, 2026
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Discard LSAs with a zero checksum value to prevent invalid LSAs from being accepted into the LSDB. Signed-off-by: kartikohlan <kartik7ohlan@gmail.com> (cherry picked from commit c29b9ed)
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The Issue: Currently, ospf_lsa_checksum_valid does not explicitly reject LSAs where the checksum field is 0x0000. In OSPF, the checksum calculation is mandatory and the value zero is reserved to indicate a checksum failure. Because Fletcher-16 uses ones-complement arithmetic, 0x0000 and 0xFFFF are mathematically equivalent, which could allow corrupted LSAs to bypass validation if the checksum field is tampered with or corrupted to 0x0000.
The Fix: Added a guard clause in ospf_lsa_checksum_valid to immediately return 0 (invalid) if lsa->checksum == 0.
Fix #20706
This is an automatic backport of pull request #20729 done by Mergify.