diff options
Diffstat (limited to 'src/kernel/arch/amd64')
| -rw-r--r-- | src/kernel/arch/amd64/pagedir.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/src/kernel/arch/amd64/pagedir.c b/src/kernel/arch/amd64/pagedir.c index 6f5fd4e..f043289 100644 --- a/src/kernel/arch/amd64/pagedir.c +++ b/src/kernel/arch/amd64/pagedir.c @@ -15,6 +15,12 @@ static void *addr_validate(void *addr) { return addr; } +static bool addr_canonical(const __user void *addr) { + const int addr_bits = 48; + uintptr_t n = (uintptr_t)addr >> addr_bits; + return (n == 0) || ((~n) << addr_bits == 0); +} + struct pagedir *pagedir_new(void) { struct pagedir *dir = page_alloc(1); @@ -57,7 +63,7 @@ get_entry(struct pagedir *dir, const void __user *virt) { pe_generic_t *pml4e, *pdpte, *pde, *pte; const union virt_addr v = {.full = (void __user *)virt}; - // TODO check if sign extension is valid + if (!addr_canonical(virt)) return NULL; pml4e = &dir->e[v.pml4]; if (!pml4e->present) return NULL; @@ -88,7 +94,7 @@ void pagedir_map(struct pagedir *dir, void __user *virt, void *phys, pe_generic_t *pml4e, *pdpte, *pde, *pte; const union virt_addr v = {.full = virt}; - // TODO check if sign extension is valid + if (!addr_canonical(virt)) return; pml4e = &dir->e[v.pml4]; if (!pml4e->present) { |