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From: Masami Hiramatsu <mhiramat@kernel.org>
To: Russell King <linux@armlinux.org.uk>
Cc: Wang Nan <wangnan0@huawei.com>, Will Deacon <will.deacon@arm.com>,
	Jon Medhurst <tixy@linaro.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, mhiramat@kernel.org,
	David Long <dave.long@linaro.org>,
	stable@vger.kernel.org
Subject: [BUGFIX PATCH v3 1/4] arm: kprobes: Fix to use get_kprobe_ctlblk after irq-disabed
Date: Fri,  4 May 2018 13:15:01 +0900	[thread overview]
Message-ID: <152540730083.29650.15621737261480060241.stgit@devbox> (raw)
In-Reply-To: <152540727123.29650.13679359124038587629.stgit@devbox>

Since get_kprobe_ctlblk() uses smp_processor_id() to access
per-cpu variable, it hits smp_processor_id sanity check as below.

[    7.006928] BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1
[    7.007859] caller is debug_smp_processor_id+0x20/0x24
[    7.008438] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.16.0-rc1-00192-g4eb17253e4b5 #1
[    7.008890] Hardware name: Generic DT based system
[    7.009917] [<c0313f0c>] (unwind_backtrace) from [<c030e6d8>] (show_stack+0x20/0x24)
[    7.010473] [<c030e6d8>] (show_stack) from [<c0c64694>] (dump_stack+0x84/0x98)
[    7.010990] [<c0c64694>] (dump_stack) from [<c071ca5c>] (check_preemption_disabled+0x138/0x13c)
[    7.011592] [<c071ca5c>] (check_preemption_disabled) from [<c071ca80>] (debug_smp_processor_id+0x20/0x24)
[    7.012214] [<c071ca80>] (debug_smp_processor_id) from [<c03335e0>] (optimized_callback+0x2c/0xe4)
[    7.013077] [<c03335e0>] (optimized_callback) from [<bf0021b0>] (0xbf0021b0)

To fix this issue, call get_kprobe_ctlblk() right after
irq-disabled since that disables preemption.

Fixes: 0dc016dbd820 ("ARM: kprobes: enable OPTPROBES for ARM 32")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: stable@vger.kernel.org
---
 arch/arm/probes/kprobes/opt-arm.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm/probes/kprobes/opt-arm.c b/arch/arm/probes/kprobes/opt-arm.c
index bcdecc25461b..ddc5a82eb10d 100644
--- a/arch/arm/probes/kprobes/opt-arm.c
+++ b/arch/arm/probes/kprobes/opt-arm.c
@@ -165,13 +165,14 @@ optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs)
 {
 	unsigned long flags;
 	struct kprobe *p = &op->kp;
-	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+	struct kprobe_ctlblk *kcb;
 
 	/* Save skipped registers */
 	regs->ARM_pc = (unsigned long)op->kp.addr;
 	regs->ARM_ORIG_r0 = ~0UL;
 
 	local_irq_save(flags);
+	kcb = get_kprobe_ctlblk();
 
 	if (kprobe_running()) {
 		kprobes_inc_nmissed_count(&op->kp);

  reply	other threads:[~2018-05-04  4:15 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-04  4:14 [BUGFIX PATCH v3 0/4] arm: kprobes: Fix to prohibit probing on unsafe functions Masami Hiramatsu
2018-05-04  4:15 ` Masami Hiramatsu [this message]
2018-05-04  4:15 ` [BUGFIX PATCH v3 2/4] arm: kprobes: Prohibit probing on optimized_callback Masami Hiramatsu
2018-05-04  4:15 ` [BUGFIX PATCH v3 3/4] arm: kprobes: Prohibit kprobes on do_undefinstr Masami Hiramatsu
2018-05-04  4:16 ` [BUGFIX PATCH v3 4/4] arm: kprobes: Prohibit kprobes on get_user functions Masami Hiramatsu
2018-05-08 11:25 ` [BUGFIX PATCH v3 0/4] arm: kprobes: Fix to prohibit probing on unsafe functions Russell King - ARM Linux
2018-05-12  0:42   ` Masami Hiramatsu
2018-05-12  4:31     ` Greg KH
2018-05-12  9:06     ` Russell King - ARM Linux
2018-05-12 11:31   ` Masami Hiramatsu
2018-05-12 17:29     ` Florian Fainelli
2018-05-13  1:55       ` Masami Hiramatsu

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