This is a note to let you know that I've just added the patch titled

arm64: __show_regs: Only resolve kernel symbols when running at EL1

to the 4.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: arm64-__show_regs-only-resolve-kernel-symbols-when-running-at-el1.patch and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

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: arm64: __show_regs: Only resolve kernel symbols when running at EL1

From: Will Deacon will.deacon@arm.com

commit a06f818a70de21b4b3b4186816094208fc7accf9 upstream.

__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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- arch/arm64/kernel/process.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)

--- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -221,8 +221,15 @@ void __show_regs(struct pt_regs *regs)

show_regs_print_info(KERN_DEFAULT); print_pstate(regs); - print_symbol("pc : %s\n", regs->pc); - print_symbol("lr : %s\n", lr); + + if (!user_mode(regs)) { + print_symbol("pc : %s\n", regs->pc); + print_symbol("lr : %s\n", lr); + } else { + printk("pc : %016llx\n", regs->pc); + printk("lr : %016llx\n", lr); + } + printk("sp : %016llx\n", sp);

i = top_reg;

Patches currently in stable-queue which might be from will.deacon@arm.com are

queue-4.15/arm64-remove-unimplemented-syscall-log-message.patch queue-4.15/arm64-mm-don-t-write-garbage-into-ttbr1_el1-register.patch queue-4.15/arm64-disable-unhandled-signal-log-messages-by-default.patch queue-4.15/irqchip-gic-v3-use-wmb-instead-of-smb_wmb-in-gic_raise_softirq.patch queue-4.15/arm64-__show_regs-only-resolve-kernel-symbols-when-running-at-el1.patch queue-4.15/arm64-cpufeature-fix-ctr_el0-field-definitions.patch queue-4.15/kbuild-always-define-endianess-in-kconfig.h.patch