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kasan: fix unaligned address is unhandled in kasan_remove_zero_shadow 

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: 0207df4fa1 ("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>
master
Lecopzer Chen 2021-01-23 21:01:25 -08:00 committed by Linus Torvalds
parent 5c447d274f
commit a11a496ee6
1 changed files with 12 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
mm/kasan/init.c
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@ -373,9 +373,10 @@ static void kasan_remove_pmd_table(pmd_t *pmd, unsigned long addr,
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);
@ -398,9 +399,10 @@ static void kasan_remove_pud_table(pud_t *pud, unsigned long addr,
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);
@ -424,9 +426,10 @@ static void kasan_remove_p4d_table(p4d_t *p4d, unsigned long addr,
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);
@ -457,9 +460,10 @@ void kasan_remove_zero_shadow(void *start, unsigned long size)
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);