From: Chen Zhongjin chenzhongjin@huawei.com
[ Upstream commit c65234b283a65cfbfc94619655e820a5e55199eb ]
kmemleak reported memory leaks in configfs_create_dir():
unreferenced object 0xffff888009f6af00 (size 192): comm "modprobe", pid 3777, jiffies 4295537735 (age 233.784s) backtrace: kmem_cache_alloc (mm/slub.c:3250 mm/slub.c:3256 mm/slub.c:3263 mm/slub.c:3273) new_fragment (./include/linux/slab.h:600 fs/configfs/dir.c:163) configfs_register_subsystem (fs/configfs/dir.c:1857) basic_write (drivers/hwtracing/stm/p_basic.c:14) stm_p_basic do_one_initcall (init/main.c:1296) do_init_module (kernel/module/main.c:2455) ...
unreferenced object 0xffff888003ba7180 (size 96): comm "modprobe", pid 3777, jiffies 4295537735 (age 233.784s) backtrace: kmem_cache_alloc (mm/slub.c:3250 mm/slub.c:3256 mm/slub.c:3263 mm/slub.c:3273) configfs_new_dirent (./include/linux/slab.h:723 fs/configfs/dir.c:194) configfs_make_dirent (fs/configfs/dir.c:248) configfs_create_dir (fs/configfs/dir.c:296) configfs_attach_group.isra.28 (fs/configfs/dir.c:816 fs/configfs/dir.c:852) configfs_register_subsystem (fs/configfs/dir.c:1881) basic_write (drivers/hwtracing/stm/p_basic.c:14) stm_p_basic do_one_initcall (init/main.c:1296) do_init_module (kernel/module/main.c:2455) ...
This is because the refcount is not correct in configfs_make_dirent(). For normal stage, the refcount is changing as:
configfs_register_subsystem() configfs_create_dir() configfs_make_dirent() configfs_new_dirent() # set s_count = 1 dentry->d_fsdata = configfs_get(sd); # s_count = 2 ... configfs_unregister_subsystem() configfs_remove_dir() remove_dir() configfs_remove_dirent() # s_count = 1 dput() ... *dentry_unlink_inode()* configfs_d_iput() # s_count = 0, release
However, if we failed in configfs_create():
configfs_register_subsystem() configfs_create_dir() configfs_make_dirent() # s_count = 2 ... configfs_create() # fail ->out_remove: configfs_remove_dirent(dentry) configfs_put(sd) # s_count = 1 return PTR_ERR(inode);
There is no inode in the error path, so the configfs_d_iput() is lost and makes sd and fragment memory leaked.
To fix this, when we failed in configfs_create(), manually call configfs_put(sd) to keep the refcount correct.
Fixes: 7063fbf22611 ("[PATCH] configfs: User-driven configuration filesystem") Signed-off-by: Chen Zhongjin chenzhongjin@huawei.com Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: Sasha Levin sashal@kernel.org --- fs/configfs/dir.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c index d1f9d2632202..ec6519e1ca3b 100644 --- a/fs/configfs/dir.c +++ b/fs/configfs/dir.c @@ -316,6 +316,7 @@ static int configfs_create_dir(struct config_item *item, struct dentry *dentry, return 0;
out_remove: + configfs_put(dentry->d_fsdata); configfs_remove_dirent(dentry); return PTR_ERR(inode); } @@ -382,6 +383,7 @@ int configfs_create_link(struct configfs_dirent *target, struct dentry *parent, return 0;
out_remove: + configfs_put(dentry->d_fsdata); configfs_remove_dirent(dentry); return PTR_ERR(inode); }