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mm: Never return page struct at 0x0, check for invalid number of pages

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This commit is contained in:
Aaron Lindsay 2012-09-29 23:26:43 -04:00
parent 375ef2eddf
commit 787a46f2ca
1 changed files with 9 additions and 0 deletions
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9
kernel/mm.c
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@ -51,6 +51,10 @@ void mm_add_free_region(void *start, void *end) {
struct page *p; struct page *p;
void *page; void *page;
//If region starts at 0x0, make it start at next page to not screw up null pointer detection, etc.
if (start == 0)
start = (char *)start + MM_PAGE_SIZE;
//make sure both start and end address are aligned to the size of a page //make sure both start and end address are aligned to the size of a page
if ((unsigned int)start % MM_PAGE_SIZE != 0) if ((unsigned int)start % MM_PAGE_SIZE != 0)
start = (char*)start + (MM_PAGE_SIZE - ((unsigned int)start % MM_PAGE_SIZE)); start = (char*)start + (MM_PAGE_SIZE - ((unsigned int)start % MM_PAGE_SIZE));
@ -89,6 +93,11 @@ struct page* mm_get_free_pages(unsigned int power) {
return (struct page*)0; return (struct page*)0;
} }
if (!num_pages) {
print("Error: mm_get_free_pages must be called with power from 0 to 31, inclusive (power=%d)\n", power);
return (struct page*)0;
}
for_each_list(it, &mm_free_page_list, struct page, list) { for_each_list(it, &mm_free_page_list, struct page, list) {
unsigned int curr_pages = 1; unsigned int curr_pages = 1;
struct page *it2; struct page *it2;