From: Alexander Gordeev agordeev@linux.ibm.com
[ 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@linux.ibm.com Signed-off-by: Alexander Gordeev agordeev@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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,