ping //Re: [PATCH v2] arm:traps: Don't print stack or raw PC/LR hex values in backtraces

From: Xiaoming Ni
Date: Mon Oct 26 2020 - 02:33:27 EST


ping

On 2020/10/16 10:31, Xiaoming Ni wrote:
Printing raw pointer values in backtraces has potential security
implications and are of questionable value anyway.

This patch follows x86 and arm64's lead and removes the "Exception stack:"
dump from kernel backtraces:
commit a25ffd3a6302a6 ("arm64: traps: Don't print stack or raw
PC/LR values in backtraces")
commit bb5e5ce545f203 ("x86/dumpstack: Remove kernel text
addresses from stack dump")

Signed-off-by: Xiaoming Ni <nixiaoming@xxxxxxxxxx>

-------
v2:
Delete [<hex numbers>] from the stack according to the email discussion
in patch V1, Other information processing will be discussed in subsequent
patches.

v1: https://lore.kernel.org/lkml/20201009075957.110017-1-nixiaoming@xxxxxxxxxx/
1. Don't print stack or raw PC/LR hex values in backtraces
2. Don't print stack mem in backtraces
3. if (!panic_on_oops), Don't print stack mem in __die()
---
arch/arm/kernel/process.c | 3 +--
arch/arm/kernel/traps.c | 4 ++--
2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 8e6ace03e960..71c9e5597d39 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -121,8 +121,7 @@ void __show_regs(struct pt_regs *regs)
printk("PC is at %pS\n", (void *)instruction_pointer(regs));
printk("LR is at %pS\n", (void *)regs->ARM_lr);
- printk("pc : [<%08lx>] lr : [<%08lx>] psr: %08lx\n",
- regs->ARM_pc, regs->ARM_lr, regs->ARM_cpsr);
+ printk("psr: %08lx\n", regs->ARM_cpsr);
printk("sp : %08lx ip : %08lx fp : %08lx\n",
regs->ARM_sp, regs->ARM_ip, regs->ARM_fp);
printk("r10: %08lx r9 : %08lx r8 : %08lx\n",
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 17d5a785df28..911bbf164875 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -68,8 +68,8 @@ void dump_backtrace_entry(unsigned long where, unsigned long from,
unsigned long end = frame + 4 + sizeof(struct pt_regs);
#ifdef CONFIG_KALLSYMS
- printk("%s[<%08lx>] (%ps) from [<%08lx>] (%pS)\n",
- loglvl, where, (void *)where, from, (void *)from);
+ printk("%s (%ps) from (%pS)\n",
+ loglvl, (void *)where, (void *)from);
#else
printk("%sFunction entered at [<%08lx>] from [<%08lx>]\n",
loglvl, where, from);