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in_collectd: reject parts with length < 4 and fix null-terminator OOB [Backport to 4.2] #11896

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Merged
cosmo0920 merged 1 commit into from
Jun 3, 2026
Merged

in_collectd: reject parts with length < 4 and fix null-terminator OOB [Backport to 4.2] #11896

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15 changes: 8 additions & 7 deletions plugins/in_collectd/netprot.c
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Original file line number Diff line number Diff line change
Expand Up @@ -247,8 +247,9 @@ int netprot_to_msgpack(char *buf, int len, struct mk_list *tdb,
part_type = be16read(buf);
part_len = be16read((unsigned char *) buf + 2);

if (len < part_len) {
flb_error("[in_collectd] data truncated (%i < %i)", len, part_len);
if (part_len < 4 || len < part_len) {
flb_error("[in_collectd] invalid part length (%i, remaining %i)",
part_len, len);
return -1;
}

Expand All @@ -268,7 +269,7 @@ int netprot_to_msgpack(char *buf, int len, struct mk_list *tdb,

switch (part_type) {
case PART_HOST:
if (ptr[size] == '\0') {
if (size > 0 && ptr[size - 1] == '\0') {
hdr.host = ptr;
}
break;
Expand All @@ -279,22 +280,22 @@ int netprot_to_msgpack(char *buf, int len, struct mk_list *tdb,
hdr.time = hr2time(be64read(ptr));
break;
case PART_PLUGIN:
if (ptr[size] == '\0') {
if (size > 0 && ptr[size - 1] == '\0') {
hdr.plugin = ptr;
}
break;
case PART_PLUGIN_INSTANCE:
if (ptr[size] == '\0') {
if (size > 0 && ptr[size - 1] == '\0') {
hdr.plugin_instance = ptr;
}
break;
case PART_TYPE:
if (ptr[size] == '\0') {
if (size > 0 && ptr[size - 1] == '\0') {
hdr.type = ptr;
Comment on lines +293 to 294

@chatgpt-codex-connector chatgpt-codex-connector Bot Jun 3, 2026

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P2 Badge Reject malformed string parts instead of keeping stale type

When a packet already set hdr.type, an empty or unterminated PART_TYPE now just skips this assignment and leaves the previous type in place, so the following PART_VALUE can be encoded under stale metadata instead of rejecting the malformed identifier. This is reachable with a multi-value collectd datagram where a later type part has part_len == 4 or lacks the trailing NUL; returning an error here (and for the other string identifiers) avoids silently corrupting the emitted metric labels.

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}
break;
case PART_TYPE_INSTANCE:
if (ptr[size] == '\0') {
if (size > 0 && ptr[size - 1] == '\0') {
hdr.type_instance = ptr;
}
break;
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