From: Matthias Kruk <m@m10k.eu>
Date: Wed, 25 Sep 2019 08:07:03 +0000 (+0900)
Subject: Ensure that PAGE_ATTR_USER is set and PAGE_ATTR_WRITABLE is not set on kernel code... 
X-Git-Url: https://git.corax.cc/?a=commitdiff_plain;h=3b9d9a644c79b8d8e88684b72f1725914904ce71;p=corax

Ensure that PAGE_ATTR_USER is set and PAGE_ATTR_WRITABLE is not set on kernel code/data segments in user-space page directories
---

diff --git a/kernel/arch/paging.c b/kernel/arch/paging.c
index d7ff02e..7f5a624 100644
--- a/kernel/arch/paging.c
+++ b/kernel/arch/paging.c
@@ -620,21 +620,26 @@ int pg_dir_create(pg_dir_t **dst)
 		 * with speculative execution behavior of certain processors
 		 */
 		for(reg = _kernel_pgdir.pd_regions; reg; reg = reg->reg_next) {
+			u32_t attrs;
+
 			switch(reg->reg_type) {
 			case REGION_TEXT:
 			case REGION_BSS:
 			case REGION_DATA:
 			case REGION_RODATA:
 			case REGION_HEAP:
-				dbg_printf("Mapping region %02x at 0x%08x:%08x\n",
-						   reg->reg_type, reg->reg_base, reg->reg_size);
+				/* make sure PAGE_ATTR_USER is set and PAGE_ATTR_WRITABLE is not set */
+				attrs = (reg->reg_attrs | PAGE_ATTR_USER) & ~PAGE_ATTR_WRITABLE;
+
+				dbg_printf("Mapping region %02x at 0x%08x:%08x (ATTR=%x)\n",
+						   reg->reg_type, reg->reg_base, reg->reg_size, attrs);
 
 				ret_val = pg_dir_map(dir, reg->reg_base, reg->reg_base,
-									 reg->reg_size, reg->reg_attrs);
+									 reg->reg_size, attrs);
 
 				if(ret_val >= 0) {
 					ret_val = _pg_dir_add_region(dir, reg->reg_base, reg->reg_size,
-												 reg->reg_type, reg->reg_attrs);
+												 reg->reg_type, attrs);
 				}
 
 				break;