From: Lecopzer Chen lecopzer@gmail.com
commit a11a496ee6e2ab6ed850233c96b94caf042af0b9 upstream.
During testing kasan_populate_early_shadow and kasan_remove_zero_shadow, if the shadow start and end address in kasan_remove_zero_shadow() is not aligned to PMD_SIZE, the remain unaligned PTE won't be removed.
In the test case for kasan_remove_zero_shadow():
shadow_start: 0xffffffb802000000, shadow end: 0xffffffbfbe000000
3-level page table: PUD_SIZE: 0x40000000 PMD_SIZE: 0x200000 PAGE_SIZE: 4K
0xffffffbf80000000 ~ 0xffffffbfbdf80000 will not be removed because in kasan_remove_pud_table(), kasan_pmd_table(*pud) is true but the next address is 0xffffffbfbdf80000 which is not aligned to PUD_SIZE.
In the correct condition, this should fallback to the next level kasan_remove_pmd_table() but the condition flow always continue to skip the unaligned part.
Fix by correcting the condition when next and addr are neither aligned.
Link: https://lkml.kernel.org/r/20210103135621.83129-1-lecopzer@gmail.com Fixes: 0207df4fa1a86 ("kernel/memremap, kasan: make ZONE_DEVICE with work with KASAN") Signed-off-by: Lecopzer Chen lecopzer.chen@mediatek.com Cc: Andrey Ryabinin aryabinin@virtuozzo.com Cc: Dan Williams dan.j.williams@intel.com Cc: Dmitry Vyukov dvyukov@google.com Cc: Alexander Potapenko glider@google.com Cc: YJ Chiang yj.chiang@mediatek.com Cc: Andrey Konovalov andreyknvl@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- mm/kasan/init.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-)
--- a/mm/kasan/init.c +++ b/mm/kasan/init.c @@ -388,9 +388,10 @@ static void kasan_remove_pmd_table(pmd_t
if (kasan_pte_table(*pmd)) { if (IS_ALIGNED(addr, PMD_SIZE) && - IS_ALIGNED(next, PMD_SIZE)) + IS_ALIGNED(next, PMD_SIZE)) { pmd_clear(pmd); - continue; + continue; + } } pte = pte_offset_kernel(pmd, addr); kasan_remove_pte_table(pte, addr, next); @@ -413,9 +414,10 @@ static void kasan_remove_pud_table(pud_t
if (kasan_pmd_table(*pud)) { if (IS_ALIGNED(addr, PUD_SIZE) && - IS_ALIGNED(next, PUD_SIZE)) + IS_ALIGNED(next, PUD_SIZE)) { pud_clear(pud); - continue; + continue; + } } pmd = pmd_offset(pud, addr); pmd_base = pmd_offset(pud, 0); @@ -439,9 +441,10 @@ static void kasan_remove_p4d_table(p4d_t
if (kasan_pud_table(*p4d)) { if (IS_ALIGNED(addr, P4D_SIZE) && - IS_ALIGNED(next, P4D_SIZE)) + IS_ALIGNED(next, P4D_SIZE)) { p4d_clear(p4d); - continue; + continue; + } } pud = pud_offset(p4d, addr); kasan_remove_pud_table(pud, addr, next); @@ -473,9 +476,10 @@ void kasan_remove_zero_shadow(void *star
if (kasan_p4d_table(*pgd)) { if (IS_ALIGNED(addr, PGDIR_SIZE) && - IS_ALIGNED(next, PGDIR_SIZE)) + IS_ALIGNED(next, PGDIR_SIZE)) { pgd_clear(pgd); - continue; + continue; + } }
p4d = p4d_offset(pgd, addr);