Hi Arnd, Russell, Linus,
Can we ensure the arm32 kprobes fix I submitted gets upstream before 5.0 final ? It takes care of an illegal instruction issue with optimized kprobes on arm32.
Here is the current state of default kprobes configuration on arm32: using them will trigger illegal instruction OOPS on v5.0-rc7, 4.19.24, v4.14.102.
My fix is in "accepted" state in the arm patch tracking system:
https://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8834/1
Should I send it directly to Linus as well ?
Thanks,
Mathieu
----- On Feb 18, 2019, at 9:55 AM, Mathieu Desnoyers mathieu.desnoyers@efficios.com wrote:
----- On Feb 18, 2019, at 7:26 AM, Greg Kroah-Hartman gregkh@linuxfoundation.org wrote:
On Wed, Feb 06, 2019 at 01:41:15PM +0900, Masami Hiramatsu wrote:
On Tue, 5 Feb 2019 15:06:10 +0000 Kees Cook keescook@chromium.org wrote:
On Mon, Feb 4, 2019 at 7:15 PM Mathieu Desnoyers mathieu.desnoyers@efficios.com wrote:
Hi,
I notice this commit as a possible culprit of the illegal instructions my lttng users are noticing on arm32 when using kprobes on a v4.19.13 Linux kernel in a Yocto environment [1]. They were able to reproduce the issue with perf as well.
commit e46daee53bb50bde38805f1823a182979724c229 Author: Kees Cook keescook@chromium.org Date: Tue Oct 30 22:12:56 2018 +0100
ARM: 8806/1: kprobes: Fix false positive with FORTIFY_SOURCEI *think* the intent there was to do
memcpy(code, &optprobe_template_entry,
memcpy(code, (unsigned long *)&optprobe_template_entry,But if you look at the commit, the "&" seems to have been stripped away, which happens to change the behavior significantly.
Yeah, this was a typo on my part. :(
Ah, I thought it had been fixed as same as x86. On x86, all optprobe_template_* are defined as kprobe_opcode_t [], but on arm, it still be kprobe_opcode_t.
Hmm, but I think we should use kprobe_opcode_t [] or char[] as asm/sections.h does. OK, I'll prepare for the change.
Did this ever get fixed in Linus's tree? If so, what is the git commit id, I can't seem to find anything...
It seems to still be in the arm patch tracking system:
https://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8834/1
If I understand its status correctly, it is applied to the arm tree, but perhaps it has not been pulled by Linus yet ? The code is still broken in Linus' master.
It would be important to get this arm kprobes fix upstream before 5.0 final.
Thanks,
Mathieu
-- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com