Messages in this thread Patch in this message | | | From | yangbo@deepin ... | Subject | [PATCH] x86/kprobe: unbalanced preempt counter with CONFIG_PREEMPT=y | Date | Mon, 15 Jan 2018 12:25:01 +0800 |
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From: Yang Bo <yangbo@deepin.com>
For each kprobe hook, preempt_disable() is called twice, but preempt_enable() is called once, when CONFIG_PREEMPT=y. No matter kprobe uses ftrace or int3. Then the preempt counter overflows, the process might be preempted and migrate to another cpu. It causes the kprobe int3 being treated as not kprobe's int3, kernel dies.
The backtrace looks like this:
int3: 0000 [#1] PREEMPT SMP Modules linkedd in: ... CPU: 1 PID: 2618 COMM: ... Hardware: ... task: ... RIP: 0010[<ffffffff81457cd5>] [<ffffffff81457cd5>] jprobe_return_end+0x0/0xb ... RIP [<ffffffff81457cd5>] jprobe_return_end+0x0/0xb RSP ...
Signed-off-by: Yang Bo <yangbo@deepin.com> --- arch/x86/kernel/kprobes/core.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index bd36f3c33cd0..1ea5c9caa8f1 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -611,6 +611,7 @@ static void setup_singlestep(struct kprobe *p, struct pt_regs *regs, regs->ip = (unsigned long)p->addr; else regs->ip = (unsigned long)p->ainsn.insn; + preempt_enable_no_resched(); } NOKPROBE_SYMBOL(setup_singlestep); -- 2.15.1
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