This is a note to let you know that I've just added the patch titled
ARC: stack unwinding: avoid indefinite looping
to the 5.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arc-stack-unwinding-avoid-indefinite-looping.patch
and it can be found in the queue-5.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 328d2168ca524d501fc4b133d6be076142bd305c Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Date: Tue, 27 Oct 2020 15:01:17 -0700
Subject: ARC: stack unwinding: avoid indefinite looping
From: Vineet Gupta <vgupta@xxxxxxxxxxxx>
commit 328d2168ca524d501fc4b133d6be076142bd305c upstream.
Currently stack unwinder is a while(1) loop which relies on the dwarf
unwinder to signal termination, which in turn relies on dwarf info to do
so. This in theory could cause an infinite loop if the dwarf info was
somehow messed up or the register contents were etc.
This fix thus detects the excessive looping and breaks the loop.
| Mem: 26184K used, 1009136K free, 0K shrd, 0K buff, 14416K cached
| CPU: 0.0% usr 72.8% sys 0.0% nic 27.1% idle 0.0% io 0.0% irq 0.0% sirq
| Load average: 4.33 2.60 1.11 2/74 139
| PID PPID USER STAT VSZ %VSZ CPU %CPU COMMAND
| 133 2 root SWN 0 0.0 3 22.9 [rcu_torture_rea]
| 132 2 root SWN 0 0.0 0 22.0 [rcu_torture_rea]
| 131 2 root SWN 0 0.0 3 21.5 [rcu_torture_rea]
| 126 2 root RW 0 0.0 2 5.4 [rcu_torture_wri]
| 129 2 root SWN 0 0.0 0 0.2 [rcu_torture_fak]
| 137 2 root SW 0 0.0 0 0.2 [rcu_torture_cbf]
| 127 2 root SWN 0 0.0 0 0.1 [rcu_torture_fak]
| 138 115 root R 1464 0.1 2 0.1 top
| 130 2 root SWN 0 0.0 0 0.1 [rcu_torture_fak]
| 128 2 root SWN 0 0.0 0 0.1 [rcu_torture_fak]
| 115 1 root S 1472 0.1 1 0.0 -/bin/sh
| 104 1 root S 1464 0.1 0 0.0 inetd
| 1 0 root S 1456 0.1 2 0.0 init
| 78 1 root S 1456 0.1 0 0.0 syslogd -O /var/log/messages
| 134 2 root SW 0 0.0 2 0.0 [rcu_torture_sta]
| 10 2 root IW 0 0.0 1 0.0 [rcu_preempt]
| 88 2 root IW 0 0.0 1 0.0 [kworker/1:1-eve]
| 66 2 root IW 0 0.0 2 0.0 [kworker/2:2-eve]
| 39 2 root IW 0 0.0 2 0.0 [kworker/2:1-eve]
| unwinder looping too long, aborting !
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arc/kernel/stacktrace.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
--- a/arch/arc/kernel/stacktrace.c
+++ b/arch/arc/kernel/stacktrace.c
@@ -112,7 +112,7 @@ arc_unwind_core(struct task_struct *tsk,
int (*consumer_fn) (unsigned int, void *), void *arg)
{
#ifdef CONFIG_ARC_DW2_UNWIND
- int ret = 0;
+ int ret = 0, cnt = 0;
unsigned int address;
struct unwind_frame_info frame_info;
@@ -132,6 +132,11 @@ arc_unwind_core(struct task_struct *tsk,
break;
frame_info.regs.r63 = frame_info.regs.r31;
+
+ if (cnt++ > 128) {
+ printk("unwinder looping too long, aborting !\n");
+ return 0;
+ }
}
return address; /* return the last address it saw */
Patches currently in stable-queue which might be from vgupta@xxxxxxxxxxxx are
queue-5.9/arc-stack-unwinding-avoid-indefinite-looping.patch
