[PATCH] lightnvm: fix possible uninitialized-variable access in nvme_nvm_submit_user_cmd()

[Tuo Li]

The variable metadata_dma is not initialized at the beginning of the
function nvme_nvm_submit_user_cmd(). If the parameter ubuf is NULL, it
remains uninitialized at the label err_meta. However, it is accessed
through the function dma_pool_free() if meta_buf is not NULL and
meta_len is not zero. In fact, ubuf, meta_buf and meta_len can come from
user space which indicates this can happen.

To fix this possible bug, only when ubuf and meta_buf are not NULL, and
bufflen and meta_len are not zero, the function dma_pool_free() is
called.

Reported-by: TOTE Robot <oslab at tsinghua.edu.cn>
Signed-off-by: Tuo Li <islituo at gmail.com>
---
 drivers/nvme/host/lightnvm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvme/host/lightnvm.c b/drivers/nvme/host/lightnvm.c
index e9d9ad47f70f..3d9fd098bd83 100644
--- a/drivers/nvme/host/lightnvm.c
+++ b/drivers/nvme/host/lightnvm.c
@@ -835,7 +835,7 @@ static int nvme_nvm_submit_user_cmd(struct request_queue *q,
 			ret = -EFAULT;
 	}
 err_meta:
-	if (meta_buf && meta_len)
+	if (ubuf && bufflen && meta_buf && meta_len)
 		dma_pool_free(dev->dma_pool, metadata, metadata_dma);
 err_map:
 	if (bio)
-- 
2.25.1