On 8/26/19 8:11 AM, Vlastimil Babka wrote:
On 7/20/19 1:32 AM, Ralph Campbell wrote:
When CONFIG_MIGRATE_VMA_HELPER is enabled, migrate_vma() calls
migrate_vma_collect() which initializes a struct mm_walk but
didn't initialize mm_walk.pud_entry. (Found by code inspection)
Use a C structure initialization to make sure it is set to NULL.
Fixes: 8763cb45ab967 ("mm/migrate: new memory migration helper for use with
device memory")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Ralph Campbell <rcampbell@xxxxxxxxxx>
Cc: "Jérôme Glisse" <jglisse@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
So this bug can manifest by some garbage address on stack being called, right? I
wonder, how comes it didn't actually happen yet?
Right.
Probably because HMM isn't widely being used in production yet.
---
mm/migrate.c | 17 +++++++----------
1 file changed, 7 insertions(+), 10 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index 515718392b24..a42858d8e00b 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2340,16 +2340,13 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
static void migrate_vma_collect(struct migrate_vma *migrate)
{
struct mmu_notifier_range range;
- struct mm_walk mm_walk;
-
- mm_walk.pmd_entry = migrate_vma_collect_pmd;
- mm_walk.pte_entry = NULL;
- mm_walk.pte_hole = migrate_vma_collect_hole;
- mm_walk.hugetlb_entry = NULL;
- mm_walk.test_walk = NULL;
- mm_walk.vma = migrate->vma;
- mm_walk.mm = migrate->vma->vm_mm;
- mm_walk.private = migrate;
+ struct mm_walk mm_walk = {
+ .pmd_entry = migrate_vma_collect_pmd,
+ .pte_hole = migrate_vma_collect_hole,
+ .vma = migrate->vma,
+ .mm = migrate->vma->vm_mm,
+ .private = migrate,
+ };
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm_walk.mm,
migrate->start,
