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Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull kthread fix from Thomas Gleixner:
 "A single fix which prevents a use after free when kthread fork fails"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  kthread: Fix use-after-free if kthread fork fails
This commit is contained in:
Linus Torvalds 2017-05-27 08:52:27 -07:00
commit d024baa58a
1 changed files with 12 additions and 5 deletions
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17
kernel/fork.c
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@ -1577,6 +1577,18 @@ static __latent_entropy struct task_struct *copy_process(
if (!p) if (!p)
goto fork_out; goto fork_out;
/*
* This _must_ happen before we call free_task(), i.e. before we jump
* to any of the bad_fork_* labels. This is to avoid freeing
* p->set_child_tid which is (ab)used as a kthread's data pointer for
* kernel threads (PF_KTHREAD).
*/
p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
/*
* Clear TID on mm_release()?
*/
p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL;
ftrace_graph_init_task(p); ftrace_graph_init_task(p);
rt_mutex_init_task(p); rt_mutex_init_task(p);
@ -1743,11 +1755,6 @@ static __latent_entropy struct task_struct *copy_process(
} }
} }
p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
/*
* Clear TID on mm_release()?
*/
p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL;
#ifdef CONFIG_BLOCK #ifdef CONFIG_BLOCK
p->plug = NULL; p->plug = NULL;
#endif #endif