Messages in this thread Patch in this message | | | From | Roman Pen <> | Subject | [PATCH 1/2] x86/dumpstack: on oops do not rewind stack for kthread | Date | Wed, 21 Sep 2016 17:43:49 +0200 |
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kthread uses stack and keeps completion structure on it to be woken up on vfork_done completion.
In commit 2deb4be28 Andy Lutomirski rewinds the stack unconditionally and further completion of task->vfork_done for any kthread leads to stack corruption (or infinite spin on attempt to spin lock on garbage memory).
Signed-off-by: Roman Pen <roman.penyaev@profitbricks.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> 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: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org --- arch/x86/kernel/dumpstack.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index e0648f7..74be764 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -250,9 +250,14 @@ void oops_end(unsigned long flags, struct pt_regs *regs, int signr) /* * We're not going to return, but we might be on an IST stack or * have very little stack space left. Rewind the stack and kill - * the task. + * the task. But kthread is a special case, since kthread uses + * stack to keep completion structure to be woken on vfork_done + * completion. */ - rewind_stack_do_exit(signr); + if (current->flags & PF_KTHREAD) + do_exit(signr); + else + rewind_stack_do_exit(signr); } NOKPROBE_SYMBOL(oops_end); -- 2.9.3
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