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: sta...@vger.kernel.org Signed-off-by: Ralph Campbell <rcampb...@nvidia.com> Cc: "Jérôme Glisse" <jgli...@redhat.com> Cc: Andrew Morton <a...@linux-foundation.org>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,
