[PATCH 5.15 066/177] net: hns3: fix race condition in debugfs

Greg Kroah-Hartman
2021-12-20T14:57:24Z

From: Yufeng Mo <moyufeng@huawei.com>

[ Upstream commit 6dde452bceca3f2ed2b33bc46a16ff5682a03a2e ]

When multiple threads concurrently access the debugfs content, data
and pointer exceptions may occur. Therefore, mutex lock protection is
added for debugfs.

Fixes: 5e69ea7ee2a6 ("net: hns3: refactor the debugfs process")
Signed-off-by: Yufeng Mo <moyufeng@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/hisilicon/hns3/hnae3.h | 2 ++
.../ethernet/hisilicon/hns3/hns3_debugfs.c | 20 +++++++++++++------
2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/hisilicon/hns3/hnae3.h b/drivers/net/ethernet/hisilicon/hns3/hnae3.h
index d701451596c82..47bba4c62f040 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hnae3.h
+++ b/drivers/net/ethernet/hisilicon/hns3/hnae3.h
@@ -830,6 +830,8 @@ struct hnae3_handle {

u8 netdev_flags;
struct dentry *hnae3_dbgfs;
+ /* protects concurrent contention between debugfs commands */
+ struct mutex dbgfs_lock;

/* Network interface message level enabled bits */
u32 msg_enable;
diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.c b/drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.c
index e54f96251fea9..3205849bdb95b 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.c
@@ -1021,6 +1021,7 @@ static ssize_t hns3_dbg_read(struct file *filp, char __user *buffer,
if (ret)
return ret;

+ mutex_lock(&handle->dbgfs_lock);
save_buf = &hns3_dbg_cmd[index].buf;

if (!test_bit(HNS3_NIC_STATE_INITED, &priv->state) ||
@@ -1033,15 +1034,15 @@ static ssize_t hns3_dbg_read(struct file *filp, char __user *buffer,
read_buf = *save_buf;
} else {
read_buf = kvzalloc(hns3_dbg_cmd[index].buf_len, GFP_KERNEL);
- if (!read_buf)
- return -ENOMEM;
+ if (!read_buf) {
+ ret = -ENOMEM;
+ goto out;
+ }

/* save the buffer addr until the last read operation */
*save_buf = read_buf;
- }

- /* get data ready for the first time to read */
- if (!*ppos) {
+ /* get data ready for the first time to read */
ret = hns3_dbg_read_cmd(dbg_data, hns3_dbg_cmd[index].cmd,
read_buf, hns3_dbg_cmd[index].buf_len);
if (ret)
@@ -1050,8 +1051,10 @@ static ssize_t hns3_dbg_read(struct file *filp, char __user *buffer,

size = simple_read_from_buffer(buffer, count, ppos, read_buf,
strlen(read_buf));
- if (size > 0)
+ if (size > 0) {
+ mutex_unlock(&handle->dbgfs_lock);
return size;
+ }

out:
/* free the buffer for the last read operation */
@@ -1060,6 +1063,7 @@ static ssize_t hns3_dbg_read(struct file *filp, char __user *buffer,
*save_buf = NULL;
}

+ mutex_unlock(&handle->dbgfs_lock);
return ret;
}

@@ -1132,6 +1136,8 @@ int hns3_dbg_init(struct hnae3_handle *handle)
debugfs_create_dir(hns3_dbg_dentry[i].name,
handle->hnae3_dbgfs);

+ mutex_init(&handle->dbgfs_lock);
+
for (i = 0; i < ARRAY_SIZE(hns3_dbg_cmd); i++) {
if ((hns3_dbg_cmd[i].cmd == HNAE3_DBG_CMD_TM_NODES &&
ae_dev->dev_version <= HNAE3_DEVICE_VERSION_V2) ||
@@ -1158,6 +1164,7 @@ int hns3_dbg_init(struct hnae3_handle *handle)
return 0;

out:
+ mutex_destroy(&handle->dbgfs_lock);
debugfs_remove_recursive(handle->hnae3_dbgfs);
handle->hnae3_dbgfs = NULL;
return ret;
@@ -1173,6 +1180,7 @@ void hns3_dbg_uninit(struct hnae3_handle *handle)
hns3_dbg_cmd[i].buf = NULL;
}

+ mutex_destroy(&handle->dbgfs_lock);
debugfs_remove_recursive(handle->hnae3_dbgfs);
handle->hnae3_dbgfs = NULL;
}
--
2.33.0