On Tue, 5 Feb 2019 15:06:10 +0000 Kees Cook <keescook@xxxxxxxxxxxx> wrote: > On Mon, Feb 4, 2019 at 7:15 PM Mathieu Desnoyers > <mathieu.desnoyers@xxxxxxxxxxxx> 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@xxxxxxxxxxxx> > > Date: Tue Oct 30 22:12:56 2018 +0100 > > > > ARM: 8806/1: kprobes: Fix false positive with FORTIFY_SOURCE > > > > I *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. Thank you, > > > Has this change ever been runtime-tested ? > > I thought I had, given the details from the original bug report, but > clearly it didn't exercise it. > > Thanks for fixing this! > > -Kees > > > > > It has been backported to: > > - 4.19 stable as commit 3fe0c68aea21 > > - 4.14 stable as commit f9e0bc710347 > > > > Thanks, > > > > Mathieu > > > > [1] https://bugs.lttng.org/issues/1174 > > > > -- > > Mathieu Desnoyers > > EfficiOS Inc. > > http://www.efficios.com > > > > -- > Kees Cook -- Masami Hiramatsu <mhiramat@xxxxxxxxxx>
