On Mon, Sep 6, 2021 at 12:13 PM Dongliang Mu <mudongliangabcd@xxxxxxxxx> wrote:
>
> The commit 8fd0c1b0647a ("nilfs2: fix memory leak in
> nilfs_sysfs_delete_device_group") adds a kobject_put to free the leaking
> object name. However, it is incomplete to only add kobject_put in the
> nilfs_sysfs_delete_device_group. The function
> nilfs_sysfs_create_device_group also needs the kobject_put to
> free the object name in the error handling part.
>
> Fix this by adding kobject_put in the error handling code of
> nilfs_sysfs_create_device_group.
Even after I add this patch, my local syzkaller still reports this
memory leak one hour later. Therefore, there are some other paths or
magics which can trigger the memory leak. I need to dig deeper.
Pavel, do you have any idea about this crash report?
BUG: memory leak
unreferenced object 0xffff88804a1a8a60 (size 32):
comm "syz-executor", pid 14551, jiffies 4294960586 (age 14.780s)
hex dump (first 32 bytes):
6c 6f 6f 70 35 00 00 00 00 00 00 00 00 00 00 00 loop5...........
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<ffffffff814750c6>] kstrdup+0x36/0x70
[<ffffffff81475153>] kstrdup_const+0x53/0x80
[<ffffffff822773a2>] kvasprintf_const+0xc2/0x110
[<ffffffff82337c5b>] kobject_set_name_vargs+0x3b/0xe0
[<ffffffff823385ed>] kobject_init_and_add+0x6d/0xc0
[<ffffffff81d2bd08>] nilfs_sysfs_create_device_group+0x98/0x3a0
[<ffffffff81d14fc4>] init_nilfs+0x424/0x580
[<ffffffff81d02962>] nilfs_mount+0x532/0x8c0
[<ffffffff815c754b>] legacy_get_tree+0x2b/0x90
[<ffffffff81565158>] vfs_get_tree+0x28/0x100
[<ffffffff815a3a82>] path_mount+0xb92/0xfe0
[<ffffffff815a3f71>] do_mount+0xa1/0xc0
[<ffffffff815a4584>] __x64_sys_mount+0xf4/0x160
[<ffffffff8433fd35>] do_syscall_64+0x35/0xb0
[<ffffffff84400068>] entry_SYSCALL_64_after_hwframe+0x44/0xae
>
> Signed-off-by: Dongliang Mu <mudongliangabcd@xxxxxxxxx>
> ---
> fs/nilfs2/sysfs.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/fs/nilfs2/sysfs.c b/fs/nilfs2/sysfs.c
> index 68e8d61e28dd..7ab60711ca76 100644
> --- a/fs/nilfs2/sysfs.c
> +++ b/fs/nilfs2/sysfs.c
> @@ -1024,6 +1024,7 @@ int nilfs_sysfs_create_device_group(struct super_block *sb)
>
> cleanup_dev_kobject:
> kobject_del(&nilfs->ns_dev_kobj);
> + kobject_put(&nilfs->ns_dev_kobj);
>
> free_dev_subgroups:
> kfree(nilfs->ns_dev_subgroups);
> --
> 2.25.1
>
