Changeset 5a5269d in mainline for kernel/generic/src/mm/as.c

Timestamp:

2019-07-02T12:03:55Z (5 years ago)

Author:

GitHub <noreply@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

98c4c16

Parents:

aca97582

git-author:

Jiří Zárevúcky <zarevucky.jiri@…> (2019-07-02 12:03:55)

git-committer:

GitHub <noreply@…> (2019-07-02 12:03:55)

Message:

Change type of uspace pointers in kernel from pointer type to numeric (#170)

From kernel's perspective, userspace addresses are not valid pointers,
and can only be used in calls to copy_to/from_uspace().
Therefore, we change the type of those arguments and variables to
uspace_addr_t which is an alias for sysarg_t.

This allows the compiler to catch accidental direct accesses to
userspace addresses.

Additionally, to avoid losing the type information in code,
a macro uspace_ptr(type) is used that translates to uspace_addr_t.
I makes no functional difference, but allows keeping the type information
in code in case we implement some sort of static checking for it in the future.

However, ccheck doesn't like that, so instead of using uspace_ptr(char),
we use uspace_ptr_char which is defined as
#define uspace_ptr_char uspace_ptr(char).

File:

• kernel/generic/src/mm/as.c (modified) (4 diffs)

kernel/generic/src/mm/as.c

@@ -2092 +2092 @@
 
 sysarg_t sys_as_area_create(uintptr_t base, size_t size, unsigned int flags,
-    uintptr_t bound, as_area_pager_info_t *pager_info)
+    uintptr_t bound, uspace_ptr_as_area_pager_info_t pager_info)
 {
         uintptr_t virt = base;
@@ -2098 +2098 @@
         mem_backend_data_t backend_data;
 
-        if (pager_info == AS_AREA_UNPAGED)
+        if (!pager_info)
                 backend = &anon_backend;
         else {
@@ -2125 +2125 @@
 }
 
-sys_errno_t sys_as_area_get_info(uintptr_t address, as_area_info_t *dest)
+sys_errno_t sys_as_area_get_info(uintptr_t address, uspace_ptr_as_area_info_t dest)
 {
         as_area_t *area;
+        as_area_info_t info;
+
+        /* Prevent leaking stack bytes via structure padding. */
+        memset(&info, 0, sizeof(info));
 
         mutex_lock(&AS->lock);
@@ -2136 +2140 @@
         }
 
-        dest->start_addr = area->base;
-        dest->size = P2SZ(area->pages);
-        dest->flags = area->flags;
+        info.start_addr = area->base;
+        info.size = P2SZ(area->pages);
+        info.flags = area->flags;
 
         mutex_unlock(&area->lock);
         mutex_unlock(&AS->lock);
+
+        copy_to_uspace(dest, &info, sizeof(info));
         return EOK;
 }