reject too-short PROXY v2 address length in mod_remoteip#683
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notroj
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Jul 17, 2026
| switch (hdr->v2.fam) { | ||
| case 0x11: /* TCPv4 */ | ||
| if (ntohs(hdr->v2.len) < sizeof(hdr->v2.addr.ip4)) { | ||
| ap_log_cerror(APLOG_MARK, APLOG_ERR, 0, c, APLOGNO(10595) |
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Please use APLOGNO() and let a maintainer fill in the next number as appropriate to avoid conflicts.
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Done, both are bare APLOGNO() now and I dropped the next-number bump so the file isn't touched at all.
Your concern was well founded, by the way: trunk has moved to 10597 since I opened this, and 10596 is now taken by mod_cern_meta.c, so my hardcoded number would have collided exactly as you describe.
| case 0x21: /* TCPv6 */ | ||
| #if APR_HAVE_IPV6 | ||
| if (ntohs(hdr->v2.len) < sizeof(hdr->v2.addr.ip6)) { | ||
| ap_log_cerror(APLOG_MARK, APLOG_ERR, 0, c, APLOGNO(10596) |
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Same here, this one's bare APLOGNO() too.
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remoteip_process_v2_header only bounds the advertised v2 header length from above, so a peer sending a TCPv4 or TCPv6 family with a length shorter than its address block makes the code read past what was actually received from the uninitialized ctx->header buffer and adopt those bytes as the client IP used for logging and Require ip decisions. Reject the header when ntohs(hdr->v2.len) is smaller than the family address struct, matching the existing too-long check right beside it.