[PATCH] [v4.14.y] infiniband: fix race condition between infiniband mlx4, mlx5 driver and core dumping

From: Ajay Kaher <akaher@vmware.com>
To: <aarcange@redhat.com>, <jannh@google.com>, <oleg@redhat.com>,
	<peterx@redhat.com>, <rppt@linux.ibm.com>, <jgg@mellanox.com>,
	<mhocko@suse.com>
Cc: <yishaih@mellanox.com>, <dledford@redhat.com>,
	<sean.hefty@intel.com>, <hal.rosenstock@gmail.com>,
	<matanb@mellanox.com>, <leonro@mellanox.com>,
	<linux-rdma@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<stable@vger.kernel.org>, <akaher@vmware.com>,
	<srivatsab@vmware.com>, <amakhalov@vmware.com>
Subject: [PATCH] [v4.14.y] infiniband: fix race condition between infiniband mlx4, mlx5  driver and core dumping
Date: Tue, 11 Jun 2019 02:22:17 +0530	[thread overview]
Message-ID: <1560199937-23476-1-git-send-email-akaher@vmware.com> (raw)

This patch is the extension of following upstream commit to fix
the race condition between get_task_mm() and core dumping
for IB->mlx4 and IB->mlx5 drivers:

commit 04f5866e41fb ("coredump: fix race condition between
mmget_not_zero()/get_task_mm() and core dumping")'

Thanks to Jason for pointing this.

Signed-off-by: Ajay Kaher <akaher@vmware.com>
---
 drivers/infiniband/hw/mlx4/main.c | 4 +++-
 drivers/infiniband/hw/mlx5/main.c | 3 +++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/mlx4/main.c b/drivers/infiniband/hw/mlx4/main.c
index e2beb18..0299c06 100644
--- a/drivers/infiniband/hw/mlx4/main.c
+++ b/drivers/infiniband/hw/mlx4/main.c
@@ -1197,6 +1197,8 @@ static void mlx4_ib_disassociate_ucontext(struct ib_ucontext *ibcontext)
 	 * mlx4_ib_vma_close().
 	 */
 	down_write(&owning_mm->mmap_sem);
+	if (!mmget_still_valid(owning_mm))
+		goto skip_mm;
 	for (i = 0; i < HW_BAR_COUNT; i++) {
 		vma = context->hw_bar_info[i].vma;
 		if (!vma)
@@ -1215,7 +1217,7 @@ static void mlx4_ib_disassociate_ucontext(struct ib_ucontext *ibcontext)
 		/* context going to be destroyed, should not access ops any more */
 		context->hw_bar_info[i].vma->vm_ops = NULL;
 	}
-
+skip_mm:
 	up_write(&owning_mm->mmap_sem);
 	mmput(owning_mm);
 	put_task_struct(owning_process);
diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
index 13a9206..3fbe396 100644
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -1646,6 +1646,8 @@ static void mlx5_ib_disassociate_ucontext(struct ib_ucontext *ibcontext)
 	 * mlx5_ib_vma_close.
 	 */
 	down_write(&owning_mm->mmap_sem);
+	if (!mmget_still_valid(owning_mm))
+		goto skip_mm;
 	mutex_lock(&context->vma_private_list_mutex);
 	list_for_each_entry_safe(vma_private, n, &context->vma_private_list,
 				 list) {
@@ -1662,6 +1664,7 @@ static void mlx5_ib_disassociate_ucontext(struct ib_ucontext *ibcontext)
 		kfree(vma_private);
 	}
 	mutex_unlock(&context->vma_private_list_mutex);
+skip_mm:
 	up_write(&owning_mm->mmap_sem);
 	mmput(owning_mm);
 	put_task_struct(owning_process);
-- 
2.7.4

