From 839620179e2b4e5982c53d8956d92e690d82960c Mon Sep 17 00:00:00 2001
From: Eduardo Silva <eduardo@chronosphere.io>
Date: Thu, 9 Apr 2026 12:11:52 -0600
Subject: [PATCH] server: http: fix malformed request crash paths

Fix the reproducible malformed-request crash paths in the HTTP
request lifecycle.

Handle missing Host data in directory redirects, reject malformed
range delimiters before substring parsing, and avoid reusing invalid
request state while advancing pipelined requests.

Verified by rebuilding with cmake --build build and replaying the
reported crash-inducing request fixtures against build/bin/monkey.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>

This patch is part of https://github.com/monkey/monkey/pull/434,
containing assorted CVE fixes.

Upstream-Status: Backport [https://github.com/monkey/monkey/commit/1570f41231888ae8c7fbd719704e2486a952e45d]
Signed-off-by: Gyorgy Sarvari <skandigraun@gmail.com>
---
 mk_core/mk_memory.c | 10 ++++++++++
 mk_server/mk_http.c | 46 +++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 52 insertions(+), 4 deletions(-)

diff --git a/mk_core/mk_memory.c b/mk_core/mk_memory.c
index c4073e23..008f7ac6 100644
--- a/mk_core/mk_memory.c
+++ b/mk_core/mk_memory.c
@@ -52,6 +52,16 @@ char *mk_ptr_to_buf(mk_ptr_t p)
 {
     char *buf;
 
+    if (!p.data || p.len == 0) {
+        buf = mk_mem_alloc(1);
+        if (!buf) {
+            return NULL;
+        }
+
+        buf[0] = '\0';
+        return buf;
+    }
+
     buf = mk_mem_alloc(p.len + 1);
     if (!buf) return NULL;
 
diff --git a/mk_server/mk_http.c b/mk_server/mk_http.c
index ad12a74a..f2f12554 100644
--- a/mk_server/mk_http.c
+++ b/mk_server/mk_http.c
@@ -457,6 +457,10 @@ static int mk_http_range_parse(struct mk_http_request *sr)
     if ((sep_pos = mk_string_char_search(sr->range.data, '-', sr->range.len)) < 0)
         return -1;
 
+    if (sep_pos < eq_pos) {
+        return -1;
+    }
+
     len = sr->range.len;
     sh = &sr->headers;
 
@@ -476,10 +480,16 @@ static int mk_http_range_parse(struct mk_http_request *sr)
     /* =yyy-xxx */
     if ((eq_pos + 1 != sep_pos) && (len > sep_pos + 1)) {
         buffer = mk_string_copy_substr(sr->range.data, eq_pos + 1, sep_pos);
+        if (!buffer) {
+            return -1;
+        }
         sh->ranges[0] = (unsigned long) atol(buffer);
         mk_mem_free(buffer);
 
         buffer = mk_string_copy_substr(sr->range.data, sep_pos + 1, len);
+        if (!buffer) {
+            return -1;
+        }
         sh->ranges[1] = (unsigned long) atol(buffer);
         mk_mem_free(buffer);
 
@@ -493,6 +503,9 @@ static int mk_http_range_parse(struct mk_http_request *sr)
     /* =yyy- */
     if ((eq_pos + 1 != sep_pos) && (len == sep_pos + 1)) {
         buffer = mk_string_copy_substr(sr->range.data, eq_pos + 1, len);
+        if (!buffer) {
+            return -1;
+        }
         sr->headers.ranges[0] = (unsigned long) atol(buffer);
         mk_mem_free(buffer);
 
@@ -522,7 +535,16 @@ static int mk_http_directory_redirect_check(struct mk_http_session *cs,
         return 0;
     }
 
+    if (!sr->host.data || sr->host.len <= 0) {
+        mk_http_error(MK_CLIENT_BAD_REQUEST, cs, sr, server);
+        return -1;
+    }
+
     host = mk_ptr_to_buf(sr->host);
+    if (!host) {
+        mk_http_error(MK_CLIENT_BAD_REQUEST, cs, sr, server);
+        return -1;
+    }
 
     /*
      * Add ending slash to the location string
@@ -588,6 +610,9 @@ static inline char *mk_http_index_lookup(mk_ptr_t *path_base,
     }
 
     off = path_base->len;
+    if ((size_t) off >= buf_size) {
+        return NULL;
+    }
     memcpy(buf, path_base->data, off);
 
     mk_list_foreach(head, server->index_files) {
@@ -1138,15 +1163,27 @@ int mk_http_request_end(struct mk_http_session *cs, struct mk_server *server)
     ret = mk_http_parser_more(&cs->parser, cs->body_length);
     if (ret == MK_TRUE) {
         /* Our pipeline request limit is the same that our keepalive limit */
+        if (cs->parser.i < 0 ||
+            (unsigned int) (cs->parser.i + 1) >= cs->body_length) {
+            goto shutdown;
+        }
+
         cs->counter_connections++;
         len = (cs->body_length - cs->parser.i) -1;
+        if (len <= 0) {
+            goto shutdown;
+        }
         memmove(cs->body,
                 cs->body + cs->parser.i + 1,
                 len);
         cs->body_length = len;
 
         /* Prepare for next one */
-        sr = mk_list_entry_first(&cs->request_list, struct mk_http_request, _head);
+        if (mk_list_is_empty(&cs->request_list) == 0) {
+            cs->close_now = MK_TRUE;
+            goto shutdown;
+        }
+        sr = &cs->sr_fixed;
         mk_http_request_free(sr, server);
         mk_http_request_init(cs, sr, server);
         mk_http_parser_init(&cs->parser);
@@ -1626,9 +1663,10 @@ int mk_http_sched_done(struct mk_sched_conn *conn,
     struct mk_http_request *sr;
 
     session = mk_http_session_get(conn);
-    sr = mk_list_entry_first(&session->request_list,
-                             struct mk_http_request, _head);
-    mk_plugin_stage_run_40(session, sr, server);
+    if (mk_list_is_empty(&session->request_list) != 0) {
+        sr = &session->sr_fixed;
+        mk_plugin_stage_run_40(session, sr, server);
+    }
 
     return mk_http_request_end(session, server);
 }
