x86/dumpstack: Pin the target stack when dumping it
Specifically, pin the stack in save_stack_trace_tsk() and show_trace_log_lvl(). This will prevent a crash if the target task dies before or while dumping its stack once we start freeing task stacks early. 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: Jann Horn <jann@thejh.net> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/cf0082cde65d1941a996d026f2b2cdbfaca17bfa.1474003868.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Ingo Molnar

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commit
1959a60182
@@ -218,6 +218,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
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unsigned long *stack;
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int i;
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if (!try_get_task_stack(task))
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return;
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irq_stack_end = (unsigned long *)this_cpu_read(irq_stack_ptr);
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irq_stack = irq_stack_end - (IRQ_STACK_SIZE / sizeof(long));
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@@ -253,6 +256,8 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
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pr_cont("\n");
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show_trace_log_lvl(task, regs, sp, bp, log_lvl);
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put_task_stack(task);
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}
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void show_regs(struct pt_regs *regs)
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