From: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
[ Upstream commit 3e8261003bd28208986d3c42004510083c086e24 ]
Kernel Address Sanitizer uses 3 bits per byte to
encode memory. That is the number of bits the start
and end address of a memory range is shifted right
when the corresponding shadow memory is created for
that memory range.
The used memory mapping routine expects page-aligned
addresses, while the above described 3-bit shift might
turn the shadow memory range start and end boundaries
into non-page-aligned in case the size of the original
memory range is less than (PAGE_SIZE << 3). As result,
the resulting shadow memory range could be short on one
page.
Align on page boundary the start and end addresses when
mapping a shadow memory range and avoid the described
issue in the future.
Note, that does not fix a real problem, since currently
no virtual regions of size less than (PAGE_SIZE << 3)
exist.
Reviewed-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Signed-off-by: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/s390/boot/vmem.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/arch/s390/boot/vmem.c b/arch/s390/boot/vmem.c
index acb1f8b53105b..c67f59db7a512 100644
--- a/arch/s390/boot/vmem.c
+++ b/arch/s390/boot/vmem.c
@@ -45,6 +45,13 @@ static void pgtable_populate(unsigned long addr, unsigned long end, enum populat
static pte_t pte_z;
+static inline void kasan_populate(unsigned long start, unsigned long end, enum populate_mode mode)
+{
+ start = PAGE_ALIGN_DOWN(__sha(start));
+ end = PAGE_ALIGN(__sha(end));
+ pgtable_populate(start, end, mode);
+}
+
static void kasan_populate_shadow(void)
{
pmd_t pmd_z = __pmd(__pa(kasan_early_shadow_pte) | _SEGMENT_ENTRY);
@@ -95,17 +102,17 @@ static void kasan_populate_shadow(void)
*/
for_each_physmem_usable_range(i, &start, &end)
- pgtable_populate(__sha(start), __sha(end), POPULATE_KASAN_MAP_SHADOW);
+ kasan_populate(start, end, POPULATE_KASAN_MAP_SHADOW);
if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
untracked_end = VMALLOC_START;
/* shallowly populate kasan shadow for vmalloc and modules */
- pgtable_populate(__sha(VMALLOC_START), __sha(MODULES_END), POPULATE_KASAN_SHALLOW);
+ kasan_populate(VMALLOC_START, MODULES_END, POPULATE_KASAN_SHALLOW);
} else {
untracked_end = MODULES_VADDR;
}
/* populate kasan shadow for untracked memory */
- pgtable_populate(__sha(ident_map_size), __sha(untracked_end), POPULATE_KASAN_ZERO_SHADOW);
- pgtable_populate(__sha(MODULES_END), __sha(_REGION1_SIZE), POPULATE_KASAN_ZERO_SHADOW);
+ kasan_populate(ident_map_size, untracked_end, POPULATE_KASAN_ZERO_SHADOW);
+ kasan_populate(MODULES_END, _REGION1_SIZE, POPULATE_KASAN_ZERO_SHADOW);
}
static bool kasan_pgd_populate_zero_shadow(pgd_t *pgd, unsigned long addr,
--
2.39.2
