[meta-networking,scarthgap] libcoap: patch CVE-2024-31031

diff --git a/meta-networking/recipes-devtools/libcoap/libcoap/CVE-2024-31031.patch b/meta-networking/recipes-devtools/libcoap/libcoap/CVE-2024-31031.patch
new file mode 100644
index 0000000000..bd1a88c87a
--- /dev/null
+++ b/meta-networking/recipes-devtools/libcoap/libcoap/CVE-2024-31031.patch
@@ -0,0 +1,82 @@ 
+From 214665ac4b44b1b6a7e38d4d6907ee835a174928 Mon Sep 17 00:00:00 2001
+From: Jon Shallow <supjps-libcoap@jpshallow.com>
+Date: Mon, 25 Mar 2024 20:44:48 +0000
+Subject: [PATCH] coap_pdu.c: Fix UndefinedBehaviorSanitizer:
+ undefined-behavior
+
+This fixes a reported error in coap_update_token() where a size_t
+calculation is overflowed (but all ends up with the correct value).
+
+Instead of adding an overflowed size_t, now subtract the reversed
+size_t calculation as appropriate.
+
+coap_update_option() and coap_insert_option() similarily updated.
+
+CVE: CVE-2024-31031
+Upstream-Status: Backport [https://github.com/obgm/libcoap/commit/214665ac4b44b1b6a7e38d4d6907ee835a174928]
+Signed-off-by: Peter Marko <peter.marko@siemens.com>
+---
+ src/coap_pdu.c | 33 ++++++++++++++++++++++++---------
+ 1 file changed, 24 insertions(+), 9 deletions(-)
+
+diff --git a/src/coap_pdu.c b/src/coap_pdu.c
+index afe445c8..e3be3f02 100644
+--- a/src/coap_pdu.c
++++ b/src/coap_pdu.c
+@@ -389,12 +389,15 @@ coap_update_token(coap_pdu_t *pdu, size_t len, const uint8_t *data) {
+     memmove(&pdu->token[(len + bias) - pdu->e_token_length],
+             pdu->token, pdu->used_size);
+     pdu->used_size += len + bias - pdu->e_token_length;
++    if (pdu->data) {
++      pdu->data += (len + bias) - pdu->e_token_length;
++    }
+   } else {
+     pdu->used_size -= pdu->e_token_length - (len + bias);
+     memmove(pdu->token, &pdu->token[pdu->e_token_length - (len + bias)], pdu->used_size);
+-  }
+-  if (pdu->data) {
+-    pdu->data += (len + bias) - pdu->e_token_length;
++    if (pdu->data) {
++      pdu->data -= pdu->e_token_length - (len + bias);
++    }
+   }
+ 
+   pdu->actual_token.length = len;
+@@ -641,9 +644,15 @@ coap_insert_option(coap_pdu_t *pdu, coap_option_num_t number, size_t len,
+                        number - prev_number, data, len))
+     return 0;
+ 
+-  pdu->used_size += shift - shrink;
+-  if (pdu->data)
+-    pdu->data += shift - shrink;
++  if (shift >= shrink) {
++    pdu->used_size += shift - shrink;
++    if (pdu->data)
++      pdu->data += shift - shrink;
++  } else {
++    pdu->used_size -= shrink - shift;
++    if (pdu->data)
++      pdu->data -= shrink - shift;
++  }
+   return shift;
+ }
+ 
+@@ -681,9 +690,15 @@ coap_update_option(coap_pdu_t *pdu, coap_option_num_t number, size_t len,
+                        decode.delta, data, len))
+     return 0;
+ 
+-  pdu->used_size += new_length - old_length;
+-  if (pdu->data)
+-    pdu->data += new_length - old_length;
++  if (new_length >= old_length) {
++    pdu->used_size += new_length - old_length;
++    if (pdu->data)
++      pdu->data += new_length - old_length;
++  } else {
++    pdu->used_size -= old_length - new_length;
++    if (pdu->data)
++      pdu->data -= old_length - new_length;
++  }
+   return 1;
+ }
+ 
diff --git a/meta-networking/recipes-devtools/libcoap/libcoap_4.3.4.bb b/meta-networking/recipes-devtools/libcoap/libcoap_4.3.4.bb
index 98f0f02fb8..65bf455d9b 100644
--- a/meta-networking/recipes-devtools/libcoap/libcoap_4.3.4.bb
+++ b/meta-networking/recipes-devtools/libcoap/libcoap_4.3.4.bb
@@ -10,6 +10,7 @@  LIC_FILES_CHKSUM = "file://LICENSE;md5=1978dbc41673ab1c20e64b287c8317bc"
 SRC_URI = "git://github.com/obgm/libcoap.git;branch=main;protocol=https \
            file://run-ptest \
            file://CVE-2024-0962.patch \
+           file://CVE-2024-31031.patch \
            "
 SRCREV = "5fd2f89ef068214130e5d60b7087ef48711fa615"