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fix: limit WebSocket message size to prevent unbounded memory growth #1544

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fix: limit WebSocket message size to prevent unbounded memory growth #1544

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14 changes: 14 additions & 0 deletions src/protocol.c
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,9 @@
#include "utils.h"
#include "compat.h"

// maximum allowed size for a single WebSocket message (bytes)
#define MAX_MESSAGE_SIZE (10 * 1024 * 1024)

// initial message list
static char initial_cmds[] = {SET_WINDOW_TITLE, SET_PREFERENCES};

Expand Down Expand Up @@ -286,10 +289,21 @@ int callback_tty(struct lws *wsi, enum lws_callback_reasons reason, void *user,

case LWS_CALLBACK_RECEIVE:
if (pss->buffer == NULL) {
if (len > MAX_MESSAGE_SIZE) {
lwsl_warn("WS message too large: %zu bytes (max %d)\n", len, MAX_MESSAGE_SIZE);
return -1;
}
pss->buffer = xmalloc(len);
pss->len = len;
memcpy(pss->buffer, in, len);
} else {
if (pss->len + len > MAX_MESSAGE_SIZE) {
lwsl_warn("WS message too large: %zu bytes (max %d)\n", pss->len + len, MAX_MESSAGE_SIZE);
free(pss->buffer);
pss->buffer = NULL;
pss->len = 0;
return -1;
}
pss->buffer = xrealloc(pss->buffer, pss->len + len);
memcpy(pss->buffer + pss->len, in, len);
pss->len += len;
Expand Down