linux-kernel - [PATCH v2] RDMA/rxe: Prevent from double freeing rxe_map

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Message-ID: <20211228014406.1033444-1-lizhijian@cn.fujitsu.com>
Date:   Tue, 28 Dec 2021 09:44:06 +0800
From:   Li Zhijian <lizhijian@...fujitsu.com>
To:     <zyjzyj2000@...il.com>, <jgg@...pe.ca>
CC:     <linux-rdma@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <yanjun.zhu@...ux.dev>, <rpearsonhpe@...il.com>,
        Li Zhijian <lizhijian@...fujitsu.com>,
        Jason Gunthorpe <jgg@...dia.com>
Subject: [PATCH v2] RDMA/rxe: Prevent from double freeing rxe_map_set

a same rxe_map_set could be freed twice:
rxe_reg_user_mr()
  -> rxe_mr_init_user()
    -> rxe_mr_free_map_set() # 1st
  -> rxe_drop_ref()
   ...
    -> rxe_mr_cleanup()
      -> rxe_mr_free_map_set() # 2nd

By convention, we should cleanup/free resources in the error path in the
same function where the resources are alloted in. So rxe_mr_init_user()
doesn't need to free the map_set directly.

In addition, we have to reset map_set to NULL inside rxe_mr_alloc() if needed
to prevent from map_set being double freed in rxe_mr_cleanup().

CC: Jason Gunthorpe <jgg@...dia.com>
Signed-off-by: Li Zhijian <lizhijian@...fujitsu.com>
---
V2: Fix it by a simpler way by following suggestion from Bob,
---
 drivers/infiniband/sw/rxe/rxe_mr.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/infiniband/sw/rxe/rxe_mr.c b/drivers/infiniband/sw/rxe/rxe_mr.c
index 25c78aade822..7c4cd19a9db2 100644
--- a/drivers/infiniband/sw/rxe/rxe_mr.c
+++ b/drivers/infiniband/sw/rxe/rxe_mr.c
@@ -141,6 +141,7 @@ static int rxe_mr_alloc(struct rxe_mr *mr, int num_buf, int both)
 		ret = rxe_mr_alloc_map_set(num_map, &mr->next_map_set);
 		if (ret) {
 			rxe_mr_free_map_set(mr->num_map, mr->cur_map_set);
+			mr->cur_map_set = NULL;
 			goto err_out;
 		}
 	}
@@ -214,7 +215,7 @@ int rxe_mr_init_user(struct rxe_pd *pd, u64 start, u64 length, u64 iova,
 				pr_warn("%s: Unable to get virtual address\n",
 						__func__);
 				err = -ENOMEM;
-				goto err_cleanup_map;
+				goto err_release_umem;
 			}
 
 			buf->addr = (uintptr_t)vaddr;
@@ -237,8 +238,6 @@ int rxe_mr_init_user(struct rxe_pd *pd, u64 start, u64 length, u64 iova,
 
 	return 0;
 
-err_cleanup_map:
-	rxe_mr_free_map_set(mr->num_map, mr->cur_map_set);
 err_release_umem:
 	ib_umem_release(umem);
 err_out:
-- 
2.31.1