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| author | Andy Lutomirski <luto@kernel.org> | 2016-10-31 16:11:43 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-11-01 07:39:17 +0100 |
| commit | 405c0759712f57b680f66aee9c55cd06ad1cbdef (patch) | |
| tree | 3a93cb428043131fd231b348dbe469be9dfadc30 | |
| parent | Merge tag 'spi-fix-v4.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git... (diff) | |
| download | linux-405c0759712f57b680f66aee9c55cd06ad1cbdef.tar.xz linux-405c0759712f57b680f66aee9c55cd06ad1cbdef.zip | |
fork: Add task stack refcounting sanity check and prevent premature task stack freeing
If something goes wrong with task stack refcounting and a stack
refcount hits zero too early, warn and leak it rather than
potentially freeing it early (and silently).
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/f29119c783a9680a4b4656e751b6123917ace94b.1477926663.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | kernel/fork.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index 623259fc794d..997ac1d584f7 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -315,6 +315,9 @@ static void account_kernel_stack(struct task_struct *tsk, int account) static void release_task_stack(struct task_struct *tsk) { + if (WARN_ON(tsk->state != TASK_DEAD)) + return; /* Better to leak the stack than to free prematurely */ + account_kernel_stack(tsk, -1); arch_release_thread_stack(tsk->stack); free_thread_stack(tsk); @@ -1862,6 +1865,7 @@ bad_fork_cleanup_count: atomic_dec(&p->cred->user->processes); exit_creds(p); bad_fork_free: + p->state = TASK_DEAD; put_task_stack(p); free_task(p); fork_out: |