# HG changeset patch
# User Maxim Dounin <mdounin@mdounin.ru>
# Date 1543246196 -10800
# Node ID a7ff19afbb14795fef14f599a304d0ad21052b70
# Parent  be5cb9c67c05ccaf22dab7abba78aa4c1545a8ee
Negative size buffers detection.

In the past, there were several security issues which resulted in
worker process memory disclosure due to buffers with negative size.
It looks reasonable to check for such buffers in various places,
much like we already check for zero size buffers.

While here, removed "#if 1 / #endif" around zero size buffer checks.
It looks highly unlikely that we'll disable these checks anytime soon.

diff --git a/src/core/ngx_output_chain.c b/src/core/ngx_output_chain.c
--- a/src/core/ngx_output_chain.c
+++ b/src/core/ngx_output_chain.c
@@ -126,6 +126,26 @@ ngx_output_chain(ngx_output_chain_ctx_t 
                 continue;
             }
 
+            if (bsize < 0) {
+
+                ngx_log_error(NGX_LOG_ALERT, ctx->pool->log, 0,
+                              "negative size buf in output "
+                              "t:%d r:%d f:%d %p %p-%p %p %O-%O",
+                              ctx->in->buf->temporary,
+                              ctx->in->buf->recycled,
+                              ctx->in->buf->in_file,
+                              ctx->in->buf->start,
+                              ctx->in->buf->pos,
+                              ctx->in->buf->last,
+                              ctx->in->buf->file,
+                              ctx->in->buf->file_pos,
+                              ctx->in->buf->file_last);
+
+                ngx_debug_point();
+
+                return NGX_ERROR;
+            }
+
             if (ngx_output_chain_as_is(ctx, ctx->in->buf)) {
 
                 /* move the chain link to the output chain */
@@ -665,7 +685,6 @@ ngx_chain_writer(void *data, ngx_chain_t
 
     for (size = 0; in; in = in->next) {
 
-#if 1
         if (ngx_buf_size(in->buf) == 0 && !ngx_buf_special(in->buf)) {
 
             ngx_log_error(NGX_LOG_ALERT, ctx->pool->log, 0,
@@ -685,7 +704,26 @@ ngx_chain_writer(void *data, ngx_chain_t
 
             continue;
         }
-#endif
+
+        if (ngx_buf_size(in->buf) < 0) {
+
+            ngx_log_error(NGX_LOG_ALERT, ctx->pool->log, 0,
+                          "negative size buf in chain writer "
+                          "t:%d r:%d f:%d %p %p-%p %p %O-%O",
+                          in->buf->temporary,
+                          in->buf->recycled,
+                          in->buf->in_file,
+                          in->buf->start,
+                          in->buf->pos,
+                          in->buf->last,
+                          in->buf->file,
+                          in->buf->file_pos,
+                          in->buf->file_last);
+
+            ngx_debug_point();
+
+            return NGX_ERROR;
+        }
 
         size += ngx_buf_size(in->buf);
 
@@ -709,7 +747,6 @@ ngx_chain_writer(void *data, ngx_chain_t
 
     for (cl = ctx->out; cl; cl = cl->next) {
 
-#if 1
         if (ngx_buf_size(cl->buf) == 0 && !ngx_buf_special(cl->buf)) {
 
             ngx_log_error(NGX_LOG_ALERT, ctx->pool->log, 0,
@@ -729,7 +766,26 @@ ngx_chain_writer(void *data, ngx_chain_t
 
             continue;
         }
-#endif
+
+        if (ngx_buf_size(cl->buf) < 0) {
+
+            ngx_log_error(NGX_LOG_ALERT, ctx->pool->log, 0,
+                          "negative size buf in chain writer "
+                          "t:%d r:%d f:%d %p %p-%p %p %O-%O",
+                          cl->buf->temporary,
+                          cl->buf->recycled,
+                          cl->buf->in_file,
+                          cl->buf->start,
+                          cl->buf->pos,
+                          cl->buf->last,
+                          cl->buf->file,
+                          cl->buf->file_pos,
+                          cl->buf->file_last);
+
+            ngx_debug_point();
+
+            return NGX_ERROR;
+        }
 
         size += ngx_buf_size(cl->buf);
     }
diff --git a/src/http/ngx_http_write_filter_module.c b/src/http/ngx_http_write_filter_module.c
--- a/src/http/ngx_http_write_filter_module.c
+++ b/src/http/ngx_http_write_filter_module.c
@@ -80,7 +80,6 @@ ngx_http_write_filter(ngx_http_request_t
                        cl->buf->file_pos,
                        cl->buf->file_last - cl->buf->file_pos);
 
-#if 1
         if (ngx_buf_size(cl->buf) == 0 && !ngx_buf_special(cl->buf)) {
             ngx_log_error(NGX_LOG_ALERT, c->log, 0,
                           "zero size buf in writer "
@@ -98,7 +97,24 @@ ngx_http_write_filter(ngx_http_request_t
             ngx_debug_point();
             return NGX_ERROR;
         }
-#endif
+
+        if (ngx_buf_size(cl->buf) < 0) {
+            ngx_log_error(NGX_LOG_ALERT, c->log, 0,
+                          "negative size buf in writer "
+                          "t:%d r:%d f:%d %p %p-%p %p %O-%O",
+                          cl->buf->temporary,
+                          cl->buf->recycled,
+                          cl->buf->in_file,
+                          cl->buf->start,
+                          cl->buf->pos,
+                          cl->buf->last,
+                          cl->buf->file,
+                          cl->buf->file_pos,
+                          cl->buf->file_last);
+
+            ngx_debug_point();
+            return NGX_ERROR;
+        }
 
         size += ngx_buf_size(cl->buf);
 
@@ -136,7 +152,6 @@ ngx_http_write_filter(ngx_http_request_t
                        cl->buf->file_pos,
                        cl->buf->file_last - cl->buf->file_pos);
 
-#if 1
         if (ngx_buf_size(cl->buf) == 0 && !ngx_buf_special(cl->buf)) {
             ngx_log_error(NGX_LOG_ALERT, c->log, 0,
                           "zero size buf in writer "
@@ -154,7 +169,24 @@ ngx_http_write_filter(ngx_http_request_t
             ngx_debug_point();
             return NGX_ERROR;
         }
-#endif
+
+        if (ngx_buf_size(cl->buf) < 0) {
+            ngx_log_error(NGX_LOG_ALERT, c->log, 0,
+                          "negative size buf in writer "
+                          "t:%d r:%d f:%d %p %p-%p %p %O-%O",
+                          cl->buf->temporary,
+                          cl->buf->recycled,
+                          cl->buf->in_file,
+                          cl->buf->start,
+                          cl->buf->pos,
+                          cl->buf->last,
+                          cl->buf->file,
+                          cl->buf->file_pos,
+                          cl->buf->file_last);
+
+            ngx_debug_point();
+            return NGX_ERROR;
+        }
 
         size += ngx_buf_size(cl->buf);
 
diff --git a/src/stream/ngx_stream_write_filter_module.c b/src/stream/ngx_stream_write_filter_module.c
--- a/src/stream/ngx_stream_write_filter_module.c
+++ b/src/stream/ngx_stream_write_filter_module.c
@@ -104,7 +104,6 @@ ngx_stream_write_filter(ngx_stream_sessi
                        cl->buf->file_pos,
                        cl->buf->file_last - cl->buf->file_pos);
 
-#if 1
         if (ngx_buf_size(cl->buf) == 0 && !ngx_buf_special(cl->buf)) {
             ngx_log_error(NGX_LOG_ALERT, c->log, 0,
                           "zero size buf in writer "
@@ -122,7 +121,24 @@ ngx_stream_write_filter(ngx_stream_sessi
             ngx_debug_point();
             return NGX_ERROR;
         }
-#endif
+
+        if (ngx_buf_size(cl->buf) < 0) {
+            ngx_log_error(NGX_LOG_ALERT, c->log, 0,
+                          "negative size buf in writer "
+                          "t:%d r:%d f:%d %p %p-%p %p %O-%O",
+                          cl->buf->temporary,
+                          cl->buf->recycled,
+                          cl->buf->in_file,
+                          cl->buf->start,
+                          cl->buf->pos,
+                          cl->buf->last,
+                          cl->buf->file,
+                          cl->buf->file_pos,
+                          cl->buf->file_last);
+
+            ngx_debug_point();
+            return NGX_ERROR;
+        }
 
         size += ngx_buf_size(cl->buf);
 
@@ -160,7 +176,6 @@ ngx_stream_write_filter(ngx_stream_sessi
                        cl->buf->file_pos,
                        cl->buf->file_last - cl->buf->file_pos);
 
-#if 1
         if (ngx_buf_size(cl->buf) == 0 && !ngx_buf_special(cl->buf)) {
             ngx_log_error(NGX_LOG_ALERT, c->log, 0,
                           "zero size buf in writer "
@@ -178,7 +193,24 @@ ngx_stream_write_filter(ngx_stream_sessi
             ngx_debug_point();
             return NGX_ERROR;
         }
-#endif
+
+        if (ngx_buf_size(cl->buf) < 0) {
+            ngx_log_error(NGX_LOG_ALERT, c->log, 0,
+                          "negative size buf in writer "
+                          "t:%d r:%d f:%d %p %p-%p %p %O-%O",
+                          cl->buf->temporary,
+                          cl->buf->recycled,
+                          cl->buf->in_file,
+                          cl->buf->start,
+                          cl->buf->pos,
+                          cl->buf->last,
+                          cl->buf->file,
+                          cl->buf->file_pos,
+                          cl->buf->file_last);
+
+            ngx_debug_point();
+            return NGX_ERROR;
+        }
 
         size += ngx_buf_size(cl->buf);