The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From a06f818a70de21b4b3b4186816094208fc7accf9 Mon Sep 17 00:00:00 2001
From: Will Deacon will.deacon@arm.com Date: Mon, 19 Feb 2018 16:46:57 +0000 Subject: [PATCH] arm64: __show_regs: Only resolve kernel symbols when running at EL1
__show_regs pretty prints PC and LR by attempting to map them to kernel function names to improve the utility of crash reports. Unfortunately, this mapping is applied even when the pt_regs corresponds to user mode, resulting in a KASLR oracle.
Avoid this issue by only looking up the function symbols when the register state indicates that we're actually running at EL1.
Cc: stable@vger.kernel.org Reported-by: NCSC Security security@ncsc.gov.uk Signed-off-by: Will Deacon will.deacon@arm.com
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index ad8aeb098b31..c0da6efe5465 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -220,8 +220,15 @@ void __show_regs(struct pt_regs *regs)
show_regs_print_info(KERN_DEFAULT); print_pstate(regs); - printk("pc : %pS\n", (void *)regs->pc); - printk("lr : %pS\n", (void *)lr); + + if (!user_mode(regs)) { + printk("pc : %pS\n", (void *)regs->pc); + printk("lr : %pS\n", (void *)lr); + } else { + printk("pc : %016llx\n", regs->pc); + printk("lr : %016llx\n", lr); + } + printk("sp : %016llx\n", sp);
i = top_reg;