Kernel/Memory: Fill new allocations with random data.

This should make it easier to spot uninitalized memory being used.

4 files changed, 19 insertions, 15 deletions

diff --git a/kernel/arch/i386/mmu.c b/kernel/arch/i386/mmu.c
index 9f20ce0..53aa5dd 100644
--- a/kernel/arch/i386/mmu.c
+++ b/kernel/arch/i386/mmu.c
@@ -3,6 +3,7 @@
 #include <log.h>
 #include <math.h>
 #include <mmu.h>
+#include <random.h>
 
 #define INDEX_FROM_BIT(a) (a / (32))
 #define OFFSET_FROM_BIT(a) (a % (32))
@@ -35,6 +36,7 @@ void *ksbrk(size_t s) {
     // If there is no active pagedirectory we
     // just assume that the memory is
     // already mapped.
+    get_random((void *)rc, data_end - rc);
     return (void *)rc;
   }
   // Determine whether we are approaching a unallocated table
@@ -57,6 +59,7 @@ void *ksbrk(size_t s) {
   assert(((uintptr_t)rc % PAGE_SIZE) == 0);
   memset((void *)rc, 0x00, s);
 
+  get_random((void *)rc, data_end - rc);
   return (void *)rc;
 }
 
diff --git a/kernel/cpu/syscall.c b/kernel/cpu/syscall.c
index 6b4f437..8e17ae1 100644
--- a/kernel/cpu/syscall.c
+++ b/kernel/cpu/syscall.c
@@ -18,10 +18,10 @@
 #include <scalls/recvfrom.h>
 #include <scalls/sendto.h>
 #include <scalls/shm.h>
+#include <scalls/sigaction.h>
 #include <scalls/socket.h>
 #include <scalls/stat.h>
 #include <scalls/uptime.h>
-#include <scalls/sigaction.h>
 #include <stdint.h>
 #include <string.h>
 
diff --git a/kernel/fs/ext2.c b/kernel/fs/ext2.c
index 0c226cf..6bde98b 100644
--- a/kernel/fs/ext2.c
+++ b/kernel/fs/ext2.c
@@ -58,7 +58,7 @@ void cached_read_block(uint32_t block, void *address, size_t size,
   struct BLOCK_CACHE *c = &cache[free_found];
   c->block_num = block;
   read_lba(block * block_byte_size / 512, c->block, 1024, 0);
-  return cached_read_block(block, address, size, offset);
+  cached_read_block(block, address, size, offset);
 }
 
 void ext2_read_block(uint32_t block, void *address, size_t size,
diff --git a/kernel/kmalloc.c b/kernel/kmalloc.c
index 34c466d..75bc74b 100644
--- a/kernel/kmalloc.c
+++ b/kernel/kmalloc.c
@@ -2,7 +2,8 @@
 #include <kmalloc.h>
 #include <ksbrk.h>
 #include <math.h>
-#define NEW_ALLOC_SIZE 0x30000
+#include <random.h>
+#define NEW_ALLOC_SIZE 0x20000
 
 #define IS_FREE (1 << 0)
 #define IS_FINAL (1 << 1)
@@ -142,6 +143,7 @@ void *kmalloc(size_t s) {
   free_entry->flags = 0;
   free_entry->n = new_entry;
   free_entry->magic = 0xdde51ab9410268b1;
+  get_random((void *)rc, s);
   return rc;
 }
 
@@ -215,16 +217,15 @@ void *kcalloc(size_t nelem, size_t elsize) {
 }
 
 void kfree(void *p) {
-  /*
-if (!p)
-return;
-// FIXME: This assumes that p is at the start of a allocated area.
-// Could this be avoided in a simple way?
-MallocHeader *h = (MallocHeader *)((uintptr_t)p - sizeof(MallocHeader));
-assert(h->magic == 0xdde51ab9410268b1);
-if (h->flags & IS_FREE)
-return;
-
-h->flags |= IS_FREE;
-merge_headers(h);*/
+  if (!p)
+    return;
+  // FIXME: This assumes that p is at the start of a allocated area.
+  // Could this be avoided in a simple way?
+  MallocHeader *h = (MallocHeader *)((uintptr_t)p - sizeof(MallocHeader));
+  assert(h->magic == 0xdde51ab9410268b1);
+  if (h->flags & IS_FREE)
+    return;
+
+  h->flags |= IS_FREE;
+  merge_headers(h);
 }