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libs/netdb: Fix dns_recv_response() to dns_answer_s size #18844

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Merged
acassis merged 1 commit into from
May 4, 2026
Merged

libs/netdb: Fix dns_recv_response() to dns_answer_s size #18844

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13 changes: 13 additions & 0 deletions libs/libc/netdb/lib_dnsquery.c
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Original file line number Diff line number Diff line change
Expand Up @@ -694,6 +694,19 @@ static int dns_recv_response(int sd, FAR union dns_addr_u *addr, int naddr,
break;
}

/* Verify that a complete answer header (10 bytes: type, class,
* ttl[2], len) is available before casting to dns_answer_s.
* Without this check, accessing ans->ttl and ans->type/class/len
* would be an OOB read if fewer than 10 bytes remain.
*/

if (nameptr + sizeof(struct dns_answer_s) > endofbuffer)
{
ret = -EILSEQ;
nwarn("DNS answer header truncated\n");
break;
}

ans = (FAR struct dns_answer_s *)nameptr;

ninfo("Answer: type=%04x, class=%04x, ttl=%06x, length=%04x\n",
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