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Reject oversized snapshot token_count before allocating (distributed DoS) #546

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Reject oversized snapshot token_count before allocating (distributed DoS) #546

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11 changes: 11 additions & 0 deletions ds4_distributed.c
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Original file line number Diff line number Diff line change
Expand Up @@ -7000,6 +7000,17 @@ static int dist_worker_handle_snapshot_load(
snprintf(err, sizeof(err), "invalid distributed snapshot load header");
}

/* Reject a token_count larger than the worker context up front, before the
* allocation and the read loop below. token_count is only bounded to
* ~UINT32_MAX/4 by the header check above, so without this a peer could
* drive a multi-GB malloc and a full-length socket read before the
* matching-state check further down (which also tests token_count > ctx_size)
* finally rejects the request. */
if (!err[0] && begin.token_count > (uint32_t)state->ctx_size) {
dist_discard_bytes(upstream->fd, body_bytes);
snprintf(err, sizeof(err), "snapshot token count exceeds worker context size");
}

int *tokens = NULL;
if (!err[0]) {
tokens = malloc((size_t)begin.token_count * sizeof(tokens[0]));
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