[PATCH V4] mm/ioremap: Check virtual address alignment while creating huge mappings

[Anshuman Khandual <anshuman.khandual@arm.com>]

Virtual address alignment is essential in ensuring correct clearing for all
intermediate level pgtable entries and freeing associated pgtable pages. An
unaligned address can end up randomly freeing pgtable page that potentially
still contains valid mappings. Hence also check it's alignment along with
existing phys_addr check.

Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Chintan Pandya <cpandya@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
---
Changes in V4:

- Added similar check for ioremap_try_huge_p4d() as per Toshi Kani

 lib/ioremap.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/lib/ioremap.c b/lib/ioremap.c
index 063213685563..a95161d9c883 100644
--- a/lib/ioremap.c
+++ b/lib/ioremap.c
@@ -86,6 +86,9 @@ static int ioremap_try_huge_pmd(pmd_t *pmd, unsigned long addr,
 	if ((end - addr) != PMD_SIZE)
 		return 0;
 
+	if (!IS_ALIGNED(addr, PMD_SIZE))
+		return 0;
+
 	if (!IS_ALIGNED(phys_addr, PMD_SIZE))
 		return 0;
 
@@ -126,6 +129,9 @@ static int ioremap_try_huge_pud(pud_t *pud, unsigned long addr,
 	if ((end - addr) != PUD_SIZE)
 		return 0;
 
+	if (!IS_ALIGNED(addr, PUD_SIZE))
+		return 0;
+
 	if (!IS_ALIGNED(phys_addr, PUD_SIZE))
 		return 0;
 
@@ -166,6 +172,9 @@ static int ioremap_try_huge_p4d(p4d_t *p4d, unsigned long addr,
 	if ((end - addr) != P4D_SIZE)
 		return 0;
 
+	if (!IS_ALIGNED(addr, P4D_SIZE))
+		return 0;
+
 	if (!IS_ALIGNED(phys_addr, P4D_SIZE))
 		return 0;
 
-- 
2.20.1