nginx: fix CVE-2026-42934

This patch applies the upstream fix as referenced in [2],
using the commit shown in [1].

[1] https://github.com/nginx/nginx/commit/54b7945961b2eaafc480d6b85d9635d0db1c126a
[2] https://nginx.org/en/security_advisories.html

Signed-off-by: Hetvi Thakar <hthakar@cisco.com>
Signed-off-by: Anuj Mittal <anuj.mittal@oss.qualcomm.com>

meta-webserver/recipes-httpd/nginx/files/CVE-2026-42934.patch

@@ -0,0 +1,80 @@
+From 54b7945961b2eaafc480d6b85d9635d0db1c126a Mon Sep 17 00:00:00 2001
+From: David Carlier <devnexen@gmail.com>
+Date: Sun, 12 Apr 2026 07:13:23 +0100
+Subject: [PATCH] Charset: fix buffer over-read in recode_from_utf8().
+
+When a multi-byte UTF-8 character was split across 3+ single-byte
+buffers, the saved bytes continuation path had two related bugs:
+
+ngx_utf8_decode() was called with the last saved-array index instead
+of the byte count, causing it to report "incomplete" even when the
+sequence was already complete.
+
+The subsequent ngx_memcpy() used that same index as the copy length,
+reading past the input buffer boundary.
+
+CVE: CVE-2026-42934
+Upstream-Status: Backport [https://github.com/nginx/nginx/commit/54b7945961b2eaafc480d6b85d9635d0db1c126a]
+
+(cherry picked from commit 54b7945961b2eaafc480d6b85d9635d0db1c126a)
+Signed-off-by: Hetvi Thakar <hthakar@cisco.com>
+---
+ .../modules/ngx_http_charset_filter_module.c  | 20 ++++++-------------
+ 1 file changed, 6 insertions(+), 14 deletions(-)
+
+diff --git a/src/http/modules/ngx_http_charset_filter_module.c b/src/http/modules/ngx_http_charset_filter_module.c
+index 482960040..edb2db568 100644
+--- a/src/http/modules/ngx_http_charset_filter_module.c
++++ b/src/http/modules/ngx_http_charset_filter_module.c
+@@ -689,7 +689,6 @@ ngx_http_charset_recode_from_utf8(ngx_pool_t *pool, ngx_buf_t *buf,
+     u_char        c, *p, *src, *dst, *saved, **table;
+     uint32_t      n;
+     ngx_buf_t    *b;
+-    ngx_uint_t    i;
+     ngx_chain_t  *out, *cl, **ll;
+ 
+     src = buf->pos;
+@@ -783,18 +782,12 @@ ngx_http_charset_recode_from_utf8(ngx_pool_t *pool, ngx_buf_t *buf,
+     ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pool->log, 0,
+                    "http charset utf saved: %z", ctx->saved_len);
+ 
+-    p = src;
+-
+-    for (i = ctx->saved_len; i < NGX_UTF_LEN; i++) {
+-        ctx->saved[i] = *p++;
+-
+-        if (p == buf->last) {
+-            break;
+-        }
+-    }
++    len = ngx_min(NGX_UTF_LEN - ctx->saved_len, (size_t) (buf->last - src));
++    ngx_memcpy(&ctx->saved[ctx->saved_len], src, len);
++    len += ctx->saved_len;
+ 
+     saved = ctx->saved;
+-    n = ngx_utf8_decode(&saved, i);
++    n = ngx_utf8_decode(&saved, len);
+ 
+     c = '\0';
+ 
+@@ -810,7 +803,7 @@ ngx_http_charset_recode_from_utf8(ngx_pool_t *pool, ngx_buf_t *buf,
+ 
+         /* incomplete UTF-8 symbol */
+ 
+-        if (i < NGX_UTF_LEN) {
++        if (len < NGX_UTF_LEN) {
+             out = ngx_http_charset_get_buf(pool, ctx);
+             if (out == NULL) {
+                 return NULL;
+@@ -823,8 +816,7 @@ ngx_http_charset_recode_from_utf8(ngx_pool_t *pool, ngx_buf_t *buf,
+             b->sync = 1;
+             b->shadow = buf;
+ 
+-            ngx_memcpy(&ctx->saved[ctx->saved_len], src, i);
+-            ctx->saved_len += i;
++            ctx->saved_len = len;
+ 
+             return out;
+         }
+-- 
+2.35.6

meta-webserver/recipes-httpd/nginx/nginx_1.28.3.bb

@@ -2,6 +2,7 @@ require nginx.inc
 
 SRC_URI:append = " \
     file://CVE-2026-40701.patch \
+    file://CVE-2026-42934.patch \
 "
 
 LIC_FILES_CHKSUM = "file://LICENSE;md5=3dc49537b08b14c8b66ad247bb4c4593"

meta-webserver/recipes-httpd/nginx/nginx_1.29.7.bb

@@ -2,6 +2,7 @@ require nginx.inc
 
 SRC_URI:append = " \
     file://CVE-2026-40701.patch \
+    file://CVE-2026-42934.patch \
 "
 
 # 1.28.x branch is the current stable branch, the recommended default