linux-kernel - [PATCH] arm64: use raw_smp_processor

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1455053182-31404-1-git-send-email-yang.shi@linaro.org>
Date:	Tue,  9 Feb 2016 13:26:22 -0800
From:	Yang Shi <yang.shi@...aro.org>
To:	will.deacon@....com, catalin.marinas@....com
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linaro-kernel@...ts.linaro.org, yang.shi@...aro.org
Subject: [PATCH] arm64: use raw_smp_processor_id in stack backtrace dump

dump_backtrace may be called in kthread context, which is not bound to a single
cpu, i.e. khungtaskd, then calling smp_processor_id may trigger the below bug
report:

BUG: using smp_processor_id() in preemptible [00000000] code: khungtaskd/71
caller is debug_smp_processor_id+0x1c/0x28
CPU: 3 PID: 71 Comm: khungtaskd Not tainted 4.5.0-rc1 #144
Hardware name: Freescale Layerscape 2085a RDB Board (DT)
Call trace:
[<ffffffc00008d120>] dump_backtrace+0x0/0x290
[<ffffffc00008d3d4>] show_stack+0x24/0x30
[<ffffffc0006bfd1c>] dump_stack+0x8c/0xd8
[<ffffffc0006fe56c>] check_preemption_disabled+0x184/0x188
[<ffffffc0006fe58c>] debug_smp_processor_id+0x1c/0x28
[<ffffffc00008d1a4>] dump_backtrace+0x84/0x290
[<ffffffc00008d3d4>] show_stack+0x24/0x30
[<ffffffc00012aa5c>] sched_show_task+0x16c/0x280
[<ffffffc0001f3df8>] watchdog+0x560/0x708
[<ffffffc000111bb8>] kthread+0x1b0/0x1d0
[<ffffffc0000864d0>] ret_from_fork+0x10/0x40

Replace it to raw version to prevent from the race condition.

Signed-off-by: Yang Shi <yang.shi@...aro.org>
---
 arch/arm64/kernel/traps.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index cbedd72..9abe236 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -146,7 +146,7 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
 {
 	struct stackframe frame;
-	unsigned long irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id());
+	unsigned long irq_stack_ptr = IRQ_STACK_PTR(raw_smp_processor_id());
 	int skip;
 
 	pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
-- 
2.0.2