From f085381e6d08f4c8d6882825f31accd455c54d70 Mon Sep 17 00:00:00 2001 From: Anand Jain Date: Wed, 15 Jan 2014 17:22:28 +0800 Subject: [PATCH] btrfs: fix null pointer deference at btrfs_sysfs_add_one+0x105 bdev is null when disk has disappeared and mounted with the degrade option stack trace --------- btrfs_sysfs_add_one+0x105/0x1c0 [btrfs] open_ctree+0x15f3/0x1fe0 [btrfs] btrfs_mount+0x5db/0x790 [btrfs] ? alloc_pages_current+0xa4/0x160 mount_fs+0x34/0x1b0 vfs_kern_mount+0x62/0xf0 do_mount+0x22e/0xa80 ? __get_free_pages+0x9/0x40 ? copy_mount_options+0x31/0x170 SyS_mount+0x7e/0xc0 system_call_fastpath+0x16/0x1b --------- reproducer: ------- mkfs.btrfs -draid1 -mraid1 /dev/sdc /dev/sdd (detach a disk) devmgt detach /dev/sdc [1] mount -o degrade /dev/sdd /btrfs ------- [1] github.com/anajain/devmgt.git Signed-off-by: Anand Jain Tested-by: Hidetoshi Seto Signed-off-by: Chris Mason --- fs/btrfs/sysfs.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c index 782374d8fd19..865f4cf9a769 100644 --- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -578,8 +578,14 @@ static int add_device_membership(struct btrfs_fs_info *fs_info) return -ENOMEM; list_for_each_entry(dev, &fs_devices->devices, dev_list) { - struct hd_struct *disk = dev->bdev->bd_part; - struct kobject *disk_kobj = &part_to_dev(disk)->kobj; + struct hd_struct *disk; + struct kobject *disk_kobj; + + if (!dev->bdev) + continue; + + disk = dev->bdev->bd_part; + disk_kobj = &part_to_dev(disk)->kobj; error = sysfs_create_link(fs_info->device_dir_kobj, disk_kobj, disk_kobj->name); -- 2.20.1