From: Mark Zhang <markzhang@xxxxxxxxxx>
commit a0ffb4c12f7fa89163e228e6f27df09b46631db1 upstream.
In a fork scenario, the parent and child can have same virtual address and
also share the uverbs fd. That causes to the list_for_each_entry search
return same doorbell physical page for all processes, even though that
page has been COW' or copied.
This patch takes the mm_struct into consideration during search, to make
sure that VA's belonging to different processes are not intermixed.
Resolves the malfunction of uverbs after fork in some specific cases.
Fixes: e126ba97dba9 ("mlx5: Add driver for Mellanox Connect-IB adapters")
Link: https://lore.kernel.org/r/feacc23fe0bc6e1088c6824d5583798745e72405.1622726212.git.leonro@xxxxxxxxxx
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Mark Zhang <markzhang@xxxxxxxxxx>
Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/infiniband/hw/mlx5/doorbell.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
--- a/drivers/infiniband/hw/mlx5/doorbell.c
+++ b/drivers/infiniband/hw/mlx5/doorbell.c
@@ -41,6 +41,7 @@ struct mlx5_ib_user_db_page {
struct ib_umem *umem;
unsigned long user_virt;
int refcnt;
+ struct mm_struct *mm;
};
int mlx5_ib_db_map_user(struct mlx5_ib_ucontext *context,
@@ -53,7 +54,8 @@ int mlx5_ib_db_map_user(struct mlx5_ib_u
mutex_lock(&context->db_page_mutex);
list_for_each_entry(page, &context->db_page_list, list)
- if (page->user_virt == (virt & PAGE_MASK))
+ if ((current->mm == page->mm) &&
+ (page->user_virt == (virt & PAGE_MASK)))
goto found;
page = kmalloc(sizeof(*page), GFP_KERNEL);
@@ -71,6 +73,8 @@ int mlx5_ib_db_map_user(struct mlx5_ib_u
kfree(page);
goto out;
}
+ mmgrab(current->mm);
+ page->mm = current->mm;
list_add(&page->list, &context->db_page_list);
@@ -91,6 +95,7 @@ void mlx5_ib_db_unmap_user(struct mlx5_i
if (!--db->u.user_page->refcnt) {
list_del(&db->u.user_page->list);
+ mmdrop(db->u.user_page->mm);
ib_umem_release(db->u.user_page->umem);
kfree(db->u.user_page);
}
