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Subject[PATCH v2 0/9] kprobes: Fix and improve blacklist symbols

Here is the v2 series of kprobes blacklist bugfix and improvements mainly
on x86 (since I started testing on qemu-x86).

>From v1, I just removed stable-ml from Cc (but tagged [1/9]) and added
Steve's Ack.

This has been started from discussion about KPROBE_ENENTS_ON_NOTRACE
configuration. I tried to find notrace functions which can cause kernel
crash with kprobes using following script.


cat notrace_functions | while read f ; do
if echo p:event$i $f >> /sys/kernel/debug/tracing/kprobe_events; then
echo "Probing on $f"
echo 1 > /sys/kernel/debug/tracing/events/kprobes/event$i/enable

And I found several functions which must be blacklisted.
- optprobe template code, which is just a template code and
never be executed. Moreover, since it can be copied and
reused, if we probe it, it modifies the template code and
can cause a crash. ([1/9][2/9])
- functions which is called before kprobe_int3_handler()
handles kprobes. This can cause a breakpoint recursion. ([3/9])
- IRQ entry text, which should not be probed since register/pagetable
status has not been stable at that point. ([4/9])
- Suffixed symbols, like .constprop, .part etc. Those suffixed
symbols never be blacklisted even if the non-suffixed version
has been blacklisted. ([5/9])
- hardirq tracer also works before int3 handling. ([6/9])
- preempt_check debug function also is involved in int3 handling.
- RCU debug routine is also called before kprobe_int3_handler().
- Some lockdep functions are also involved in int3 handling.

Of course there still may be some functions which can be called
by configuration change, I'll continue to test it.

Thank you,


Masami Hiramatsu (9):
x86/kprobes: Prohibit probing on optprobe template code
x86/kprobes: Move trampoline code into RODATA
x86/kprobes: Prohibit probing on functions before kprobe_int3_handler()
x86/kprobes: Prohibit probing on IRQ handlers directly
kprobes: Search non-suffixed symbol in blacklist
kprobes: Prohibit probing on hardirq tracers
kprobes: Prohibit probing on preempt_check debug functions
kprobes: Prohibit probing on RCU debug routine
kprobes: Prohibit probing on lockdep functions

arch/x86/kernel/alternative.c | 3 ++-
arch/x86/kernel/ftrace.c | 3 ++-
arch/x86/kernel/kprobes/core.c | 7 +++++++
arch/x86/kernel/kprobes/opt.c | 4 ++--
arch/x86/kernel/traps.c | 1 +
kernel/kprobes.c | 21 ++++++++++++++++++++-
kernel/locking/lockdep.c | 7 ++++++-
kernel/rcu/tree.c | 2 ++
kernel/rcu/update.c | 2 ++
kernel/trace/trace_irqsoff.c | 9 +++++++--
kernel/trace/trace_preemptirq.c | 5 +++++
lib/smp_processor_id.c | 7 +++++--
12 files changed, 61 insertions(+), 10 deletions(-)

Masami Hiramatsu (Linaro) <>

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