From: Anand Jain Date: Fri, 4 Sep 2020 17:34:21 +0000 (+0800) Subject: btrfs: fix put of uninitialized kobject after seed device delete X-Git-Tag: v5.9-rc7~30^2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b5ddcffa37778244d5e786fe32f778edf2bfc93e;p=thirdparty%2Fkernel%2Flinux.git btrfs: fix put of uninitialized kobject after seed device delete The following test case leads to NULL kobject free error: mount seed /mnt add sprout to /mnt umount /mnt mount sprout to /mnt delete seed kobject: '(null)' (00000000dd2b87e4): is not initialized, yet kobject_put() is being called. WARNING: CPU: 1 PID: 15784 at lib/kobject.c:736 kobject_put+0x80/0x350 RIP: 0010:kobject_put+0x80/0x350 :: Call Trace: btrfs_sysfs_remove_devices_dir+0x6e/0x160 [btrfs] btrfs_rm_device.cold+0xa8/0x298 [btrfs] btrfs_ioctl+0x206c/0x22a0 [btrfs] ksys_ioctl+0xe2/0x140 __x64_sys_ioctl+0x1e/0x29 do_syscall_64+0x96/0x150 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f4047c6288b :: This is because, at the end of the seed device-delete, we try to remove the seed's devid sysfs entry. But for the seed devices under the sprout fs, we don't initialize the devid kobject yet. So add a kobject state check, which takes care of the bug. Fixes: 668e48af7a94 ("btrfs: sysfs, add devid/dev_state kobject and device attributes") CC: stable@vger.kernel.org # 5.6+ Signed-off-by: Anand Jain Reviewed-by: David Sterba Signed-off-by: David Sterba --- diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c index c8df2edafd855..5be30066563c8 100644 --- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -1170,10 +1170,12 @@ int btrfs_sysfs_remove_devices_dir(struct btrfs_fs_devices *fs_devices, disk_kobj->name); } - kobject_del(&one_device->devid_kobj); - kobject_put(&one_device->devid_kobj); + if (one_device->devid_kobj.state_initialized) { + kobject_del(&one_device->devid_kobj); + kobject_put(&one_device->devid_kobj); - wait_for_completion(&one_device->kobj_unregister); + wait_for_completion(&one_device->kobj_unregister); + } return 0; } @@ -1186,10 +1188,12 @@ int btrfs_sysfs_remove_devices_dir(struct btrfs_fs_devices *fs_devices, sysfs_remove_link(fs_devices->devices_kobj, disk_kobj->name); } - kobject_del(&one_device->devid_kobj); - kobject_put(&one_device->devid_kobj); + if (one_device->devid_kobj.state_initialized) { + kobject_del(&one_device->devid_kobj); + kobject_put(&one_device->devid_kobj); - wait_for_completion(&one_device->kobj_unregister); + wait_for_completion(&one_device->kobj_unregister); + } } return 0;