[PATCH] fs/fuse/virtio_fs: Fix a potential memory allocation failure

[PATCH] fs/fuse/virtio_fs: Fix a potential memory allocation failure

[zhouchuangao]

Allocate memory for struct fuse_conn may fail, we should not jump to
out_err to kfree(fc).

Signed-off-by: zhouchuangao <zhouchuangao@vivo.com>
---
 fs/fuse/virtio_fs.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 4ee6f73..1f333c6 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -1430,11 +1430,11 @@ static int virtio_fs_get_tree(struct fs_context *fsc)
 	err = -ENOMEM;
 	fc = kzalloc(sizeof(struct fuse_conn), GFP_KERNEL);
 	if (!fc)
-		goto out_err;
+		goto out_err_fc;
 
 	fm = kzalloc(sizeof(struct fuse_mount), GFP_KERNEL);
 	if (!fm)
-		goto out_err;
+		goto out_err_fm;
 
 	fuse_conn_init(fc, fm, get_user_ns(current_user_ns()),
 		       &virtio_fs_fiq_ops, fs);
@@ -1468,8 +1468,9 @@ static int virtio_fs_get_tree(struct fs_context *fsc)
 	fsc->root = dget(sb->s_root);
 	return 0;
 
-out_err:
+out_err_fm:
 	kfree(fc);
+out_err_fc:
 	mutex_lock(&virtio_fs_mutex);
 	virtio_fs_put(fs);
 	mutex_unlock(&virtio_fs_mutex);
-- 
2.7.4

Re: [PATCH] fs/fuse/virtio_fs: Fix a potential memory allocation failure

[Connor Kuehl]

On 3/24/21 7:38 AM, zhouchuangao wrote:
> Allocate memory for struct fuse_conn may fail, we should not jump to
> out_err to kfree(fc).

Why not? If fc's allocation fails then it is NULL and calling kfree() on 
a NULL pointer is a noop[1].

Connor

[1] 
https://www.kernel.org/doc/html/latest/core-api/mm-api.html?highlight=kfree#c.kfree