diff mbox series

[PATCHv4,1/4] x86/mm/ident_map: Fix virtual address wrap to zero

Message ID 20240822124000.1171321-2-kirill.shutemov@linux.intel.com
State Superseded
Headers show
Series x86: Reduce code duplication on page table initialization | expand

Commit Message

Kirill A. Shutemov Aug. 22, 2024, 12:39 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.

The wrapping to zero only occurs if the top PGD entry is accessed.
There are no such users in the upstream. Only hibernate_64.c uses
x86_mapping_info::offset, and it operates on the direct mapping range,
which is not the top PGD entry.

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

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 arch/x86/mm/ident_map.c | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)
diff mbox series

Patch

diff --git a/arch/x86/mm/ident_map.c b/arch/x86/mm/ident_map.c
index 437e96fb4977..5872f3ee863c 100644
--- a/arch/x86/mm/ident_map.c
+++ b/arch/x86/mm/ident_map.c
@@ -101,9 +101,7 @@  static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page,
 		pmd_t *pmd;
 		bool use_gbpage;
 
-		next = (addr & PUD_MASK) + PUD_SIZE;
-		if (next > end)
-			next = end;
+		next = pud_addr_end(addr, end);
 
 		/* if this is already a gbpage, this portion is already mapped */
 		if (pud_leaf(*pud))
@@ -154,10 +152,7 @@  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);
@@ -199,10 +194,7 @@  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);