keep buflen in sync in dns_process address copy path - #13558
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moonchen
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Sep 2, 2026
bryancall
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Thank you, much appreciated |
cmcfarlen
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Sep 9, 2026
…e#13558) When decoding a DNS response, the path that copies an unaligned A or AAAA record into the host entry buffer moved the write position without updating the count of space remaining, so the two disagreed for the rest of the response. Update the count after the copy, the same way the name, CNAME and PTR paths already do. (cherry picked from commit 80e89e5)
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Cherry-picked to the 10.2.x branch as b880bea for the 10.2.1 release. |
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dns_process copies each answer record into the fixed HostEnt hostbuf while keeping a running buflen for the space left at the write cursor, but the branch that memcpys an A/AAAA address when the source is not word aligned advances the cursor by the alignment padding and the record length without decrementing buflen. Since every later name expansion hands that same buflen to dn_expand as its output limit, the stale, over-large value lets a crafted response (a large address record followed by a record whose owner name expands near the end of hostbuf) write the expanded name past the buffer and into the adjacent srv_hosts vector. This restores buflen from the cursor after the copy so it stays consistent, matching what the name, CNAME and PTR paths already do.