From: Jamie Iles jamie@nuviainc.com
[ Upstream commit ae284d87abade58c8db7760c808f311ef1ce693c ]
syzkaller found that with CONFIG_DEBUG_KOBJECT_RELEASE=y, unmounting an f2fs filesystem could result in the following splat:
kobject: 'loop5' ((____ptrval____)): kobject_release, parent 0000000000000000 (delayed 250) kobject: 'f2fs_xattr_entry-7:5' ((____ptrval____)): kobject_release, parent 0000000000000000 (delayed 750) ------------[ cut here ]------------ ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x98 WARNING: CPU: 0 PID: 699 at lib/debugobjects.c:485 debug_print_object+0x180/0x240 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 699 Comm: syz-executor.5 Tainted: G S 5.9.0-rc8+ #101 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0x0/0x4d8 show_stack+0x34/0x48 dump_stack+0x174/0x1f8 panic+0x360/0x7a0 __warn+0x244/0x2ec report_bug+0x240/0x398 bug_handler+0x50/0xc0 call_break_hook+0x160/0x1d8 brk_handler+0x30/0xc0 do_debug_exception+0x184/0x340 el1_dbg+0x48/0xb0 el1_sync_handler+0x170/0x1c8 el1_sync+0x80/0x100 debug_print_object+0x180/0x240 debug_check_no_obj_freed+0x200/0x430 slab_free_freelist_hook+0x190/0x210 kfree+0x13c/0x460 f2fs_put_super+0x624/0xa58 generic_shutdown_super+0x120/0x300 kill_block_super+0x94/0xf8 kill_f2fs_super+0x244/0x308 deactivate_locked_super+0x104/0x150 deactivate_super+0x118/0x148 cleanup_mnt+0x27c/0x3c0 __cleanup_mnt+0x28/0x38 task_work_run+0x10c/0x248 do_notify_resume+0x9d4/0x1188 work_pending+0x8/0x34c
Like the error handling for f2fs_register_sysfs(), we need to wait for the kobject to be destroyed before returning to prevent a potential use-after-free.
Fixes: bf9e697ecd42 ("f2fs: expose features to sysfs entry") Cc: Jaegeuk Kim jaegeuk@kernel.org Cc: Chao Yu chao@kernel.org Signed-off-by: Jamie Iles jamie@nuviainc.com Reviewed-by: Chao Yu yuchao0@huawei.com Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/f2fs/sysfs.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c index 9a59f49ba405..89b6c33ba6a4 100644 --- a/fs/f2fs/sysfs.c +++ b/fs/f2fs/sysfs.c @@ -717,4 +717,5 @@ void f2fs_unregister_sysfs(struct f2fs_sb_info *sbi) } kobject_del(&sbi->s_kobj); kobject_put(&sbi->s_kobj); + wait_for_completion(&sbi->s_kobj_unregister); }