From: Masami Hiramatsu <mhiramat@kernel.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: "Paul E . McKenney" <paulmck@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Joel Fernandes <joel@joelfernandes.org>,
Steven Rostedt <rostedt@goodmis.org>,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
gregkh@linuxfoundation.org, gustavo@embeddedor.com,
tglx@linutronix.de, josh@joshtriplett.org,
mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com,
stable@vger.kernel.org
Subject: [PATCH] x86/kprobes: Prohibit probing on rcu_nmi_exit() and ist_exit()
Date: Sat, 7 Mar 2020 12:02:12 +0900 [thread overview]
Message-ID: <158355013189.14191.9105069890402942867.stgit@devnote2> (raw)
Prohibit probing on rcu_nmi_exit() and ist_exit() which
are called from do_int3()'s kprobe path after kprobe_int3_handler().
The commit c13324a505c7 ("x86/kprobes: Prohibit probing on
functions before kprobe_int3_handler()") tried to fix similar
issue, but it only marks the functions before kprobe_int3_handler()
in do_int3().
If we put a kprobe on rcu_nmi_exit() or ist_exit(), the kprobes
will detect reentrance. However, it only skips the kprobe handler,
exits from do_int3() and hits ist_exit() and rcu_nmi_exit() again.
Thus, it causes another int3 exception and finally we will get
the kernel panic with "Unrecoverable kprobe detected." error message.
This is reproducible by the following commands.
/ # echo 0 > /proc/sys/debug/kprobes-optimization
/ # echo p vfs_read > /sys/kernel/debug/tracing/kprobe_events
/ # echo p rcu_nmi_exit >> /sys/kernel/debug/tracing/kprobe_events
/ # echo 1 > /sys/kernel/debug/tracing/events/kprobes/enable
Fixes: c13324a505c7 ("x86/kprobes: Prohibit probing on functions before kprobe_int3_handler()")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: stable@vger.kernel.org
---
arch/x86/kernel/traps.c | 1 +
kernel/rcu/tree.c | 1 +
2 files changed, 2 insertions(+)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 6ef00eb6fbb9..c63fb7697794 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -115,6 +115,7 @@ void ist_exit(struct pt_regs *regs)
if (!user_mode(regs))
rcu_nmi_exit();
}
+NOKPROBE_SYMBOL(ist_exit);
/**
* ist_begin_non_atomic() - begin a non-atomic section in an IST exception
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index d91c9156fab2..c49ea0e919f9 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -670,6 +670,7 @@ void rcu_nmi_exit(void)
{
rcu_nmi_exit_common(false);
}
+NOKPROBE_SYMBOL(rcu_nmi_exit);
/**
* rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle
next reply other threads:[~2020-03-07 3:02 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-07 3:02 Masami Hiramatsu [this message]
2020-03-07 3:28 ` [PATCH] x86/kprobes: Prohibit probing on rcu_nmi_exit() and ist_exit() Paul E. McKenney
2020-03-07 7:47 ` Joel Fernandes
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=158355013189.14191.9105069890402942867.stgit@devnote2 \
--to=mhiramat@kernel.org \
--cc=gregkh@linuxfoundation.org \
--cc=gustavo@embeddedor.com \
--cc=jiangshanlai@gmail.com \
--cc=joel@joelfernandes.org \
--cc=josh@joshtriplett.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mathieu.desnoyers@efficios.com \
--cc=mingo@kernel.org \
--cc=paulmck@kernel.org \
--cc=peterz@infradead.org \
--cc=rostedt@goodmis.org \
--cc=stable@vger.kernel.org \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).