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Commit 1959a601 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar
Browse files

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: default avatarAndy 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: default avatarIngo Molnar <mingo@kernel.org>
parent 23196f2e

arch/x86/kernel/dumpstack_32.c

+5 −0
Original line number Diff line number Diff line
@@ -163,6 +163,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, 
	unsigned long *stack;

	int i;



	if (!try_get_task_stack(task))

		return;



	sp = sp ? : get_stack_pointer(task, regs);



	stack = sp;
@@ -179,6 +182,8 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, 
	}

	pr_cont("\n");

	show_trace_log_lvl(task, regs, sp, bp, log_lvl);



	put_task_stack(task);

}

arch/x86/kernel/dumpstack_64.c

+5 −0
Original line number Diff line number Diff line
@@ -218,6 +218,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, 
	unsigned long *stack;

	int i;



	if (!try_get_task_stack(task))

		return;



	irq_stack_end = (unsigned long *)this_cpu_read(irq_stack_ptr);

	irq_stack     = irq_stack_end - (IRQ_STACK_SIZE / sizeof(long));
@@ -253,6 +256,8 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, 


	pr_cont("\n");

	show_trace_log_lvl(task, regs, sp, bp, log_lvl);



	put_task_stack(task);

}



void show_regs(struct pt_regs *regs)

arch/x86/kernel/stacktrace.c

+5 −0
Original line number Diff line number Diff line
@@ -79,9 +79,14 @@ void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace) 


void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)

{

	if (!try_get_task_stack(tsk))

		return;



	dump_trace(tsk, NULL, NULL, 0, &save_stack_ops_nosched, trace);

	if (trace->nr_entries < trace->max_entries)

		trace->entries[trace->nr_entries++] = ULONG_MAX;



	put_task_stack(tsk);

}

EXPORT_SYMBOL_GPL(save_stack_trace_tsk);