[PATCH 1/1] mm: fix vma_copy for !CONFIG_PER_VMA_LOCK

[Suren Baghdasaryan <surenb@google.com>]

vma_copy() function for !CONFIG_PER_VMA_LOCK configuration copies all
fields using memcpy() as opposed to CONFIG_PER_VMA_LOCK version which
copies only required fields. anon_vma_chain field should not be copied
and new vma should instead initialize it to an empty list. Fix this
by initializing anon_vma_chain inside vma_copy() function. The version
of vma_copy() for CONFIG_PER_VMA_LOCK is fine since it does not change
that field and anon_vma_chain of any new vma is already initialized and
empty.

Fixes: 85ad413389ae ("mm: make vma cache SLAB_TYPESAFE_BY_RCU")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202412082208.db1fb2c9-lkp@intel.com
Reported-by: Klara Modin <klarasmodin@gmail.com>
Closes: https://lore.kernel.org/all/d0ae7609-aca4-4497-9188-bb09e96e7768@gmail.com/
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
Applies over mm-unstable

 kernel/fork.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/fork.c b/kernel/fork.c
index fec32aa06135..d532f893e977 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -524,6 +524,7 @@ static void vma_copy(const struct vm_area_struct *src, struct vm_area_struct *de
 	 * will be reinitialized.
 	 */
 	data_race(memcpy(dest, src, sizeof(*dest)));
+	INIT_LIST_HEAD(&dest->anon_vma_chain);
 }
 
 #endif /* CONFIG_PER_VMA_LOCK */

base-commit: 6e165f54437931f329d09dca6c19d99af08a36e1
-- 
2.47.0.338.g60cca15819-goog