diff mbox series

[1/3] x86/mm/ident_map: Fix virtual address wrap to zero

Message ID 20240701124334.1855981-2-kirill.shutemov@linux.intel.com (mailing list archive)
State Handled Elsewhere, archived
Headers show
Series x86: Reduce code duplication on page table initialization | expand

Commit Message

Kirill A . Shutemov July 1, 2024, 12:43 p.m. UTC 
Calculation of 'next' virtual address doesn't protect against wrapping
to zero. It can result in page table corruption and hang. The
problematic case is possible if user sets high x86_mapping_info::offset.

Replace manual 'next' calculation with p?d_addr_and() which handles
wrapping correctly.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 arch/x86/mm/ident_map.c | 15 +++------------
 1 file changed, 3 insertions(+), 12 deletions(-)

Comments

Huang, Kai July 3, 2024, 10:11 a.m. UTC | #1 
On Mon, 2024-07-01 at 15:43 +0300, Kirill A. Shutemov wrote:
> Calculation of 'next' virtual address doesn't protect against wrapping
> to zero. It can result in page table corruption and hang. The
> problematic case is possible if user sets high x86_mapping_info::offset.
> 
> Replace manual 'next' calculation with p?d_addr_and() which handles

p?d_addr_and() -> p?d_addr_end().

> wrapping correctly.
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

Reviewed-by: Kai Huang <kai.huang@intel.com>
diff mbox series

Patch

diff --git a/arch/x86/mm/ident_map.c b/arch/x86/mm/ident_map.c
index c45127265f2f..7422146b0dc9 100644
--- a/arch/x86/mm/ident_map.c
+++ b/arch/x86/mm/ident_map.c
@@ -100,10 +100,7 @@  static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page,
 		pud_t *pud = pud_page + pud_index(addr);
 		pmd_t *pmd;
 
-		next = (addr & PUD_MASK) + PUD_SIZE;
-		if (next > end)
-			next = end;
-
+		next = pud_addr_end(addr, end);
 		if (info->direct_gbpages) {
 			pud_t pudval;
 
@@ -141,10 +138,7 @@  static int ident_p4d_init(struct x86_mapping_info *info, p4d_t *p4d_page,
 		p4d_t *p4d = p4d_page + p4d_index(addr);
 		pud_t *pud;
 
-		next = (addr & P4D_MASK) + P4D_SIZE;
-		if (next > end)
-			next = end;
-
+		next = p4d_addr_end(addr, end);
 		if (p4d_present(*p4d)) {
 			pud = pud_offset(p4d, 0);
 			result = ident_pud_init(info, pud, addr, next);
@@ -186,10 +180,7 @@  int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page,
 		pgd_t *pgd = pgd_page + pgd_index(addr);
 		p4d_t *p4d;
 
-		next = (addr & PGDIR_MASK) + PGDIR_SIZE;
-		if (next > end)
-			next = end;
-
+		next = pgd_addr_end(addr, end);
 		if (pgd_present(*pgd)) {
 			p4d = p4d_offset(pgd, 0);
 			result = ident_p4d_init(info, p4d, addr, next);