diff options
author | Oleg Nesterov <oleg@redhat.com> | 2013-06-14 21:09:47 +0200 |
---|---|---|
committer | Al Viro <viro@zeniv.linux.org.uk> | 2013-06-15 05:39:08 +0400 |
commit | e7b2c4069252732d52f1de6d1f7c82d99a156659 (patch) | |
tree | 61058c0dd3806eaf067d1e6cf1634aa1acc9336e /fs | |
parent | 698b8223631472bf982ed570b0812faa61955683 (diff) | |
download | linux-3.10-e7b2c4069252732d52f1de6d1f7c82d99a156659.tar.gz linux-3.10-e7b2c4069252732d52f1de6d1f7c82d99a156659.tar.bz2 linux-3.10-e7b2c4069252732d52f1de6d1f7c82d99a156659.zip |
fput: task_work_add() can fail if the caller has passed exit_task_work()
fput() assumes that it can't be called after exit_task_work() but
this is not true, for example free_ipc_ns()->shm_destroy() can do
this. In this case fput() silently leaks the file.
Change it to fallback to delayed_fput_work if task_work_add() fails.
The patch looks complicated but it is not, it changes the code from
if (PF_KTHREAD) {
schedule_work(...);
return;
}
task_work_add(...)
to
if (!PF_KTHREAD) {
if (!task_work_add(...))
return;
/* fallback */
}
schedule_work(...);
As for shm_destroy() in particular, we could make another fix but I
think this change makes sense anyway. There could be another similar
user, it is not safe to assume that task_work_add() can't fail.
Reported-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/file_table.c | 19 |
1 files changed, 10 insertions, 9 deletions
diff --git a/fs/file_table.c b/fs/file_table.c index cd4d87a8295..485dc0eddd6 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -306,17 +306,18 @@ void fput(struct file *file) { if (atomic_long_dec_and_test(&file->f_count)) { struct task_struct *task = current; + unsigned long flags; + file_sb_list_del(file); - if (unlikely(in_interrupt() || task->flags & PF_KTHREAD)) { - unsigned long flags; - spin_lock_irqsave(&delayed_fput_lock, flags); - list_add(&file->f_u.fu_list, &delayed_fput_list); - schedule_work(&delayed_fput_work); - spin_unlock_irqrestore(&delayed_fput_lock, flags); - return; + if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) { + init_task_work(&file->f_u.fu_rcuhead, ____fput); + if (!task_work_add(task, &file->f_u.fu_rcuhead, true)) + return; } - init_task_work(&file->f_u.fu_rcuhead, ____fput); - task_work_add(task, &file->f_u.fu_rcuhead, true); + spin_lock_irqsave(&delayed_fput_lock, flags); + list_add(&file->f_u.fu_list, &delayed_fput_list); + schedule_work(&delayed_fput_work); + spin_unlock_irqrestore(&delayed_fput_lock, flags); } } |