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x86/dumpstack: Pin the target stack when dumping it

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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>
This commit is contained in:
Andy Lutomirski 2016-09-15 22:45:45 -07:00 committed by Ingo Molnar
parent 23196f2e5f
commit 1959a60182
3 changed files with 15 additions and 0 deletions
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5
arch/x86/kernel/dumpstack_32.c
View File

@ -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);
}

5
arch/x86/kernel/dumpstack_64.c
View File

@ -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)

5
arch/x86/kernel/stacktrace.c
View File

@ -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);