This is a note to let you know that I've just added the patch titled
kprobes: Fix to handle forcibly unoptimized kprobes on freeing_list
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kprobes-fix-to-handle-forcibly-unoptimized-kprobes-on-freeing_list.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4fbd2f83fda0ca44a2ec6421ca3508b355b31858 Mon Sep 17 00:00:00 2001
From: "Masami Hiramatsu (Google)" <mhiramat@xxxxxxxxxx>
Date: Tue, 21 Feb 2023 08:49:16 +0900
Subject: kprobes: Fix to handle forcibly unoptimized kprobes on freeing_list
From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
commit 4fbd2f83fda0ca44a2ec6421ca3508b355b31858 upstream.
Since forcibly unoptimized kprobes will be put on the freeing_list directly
in the unoptimize_kprobe(), do_unoptimize_kprobes() must continue to check
the freeing_list even if unoptimizing_list is empty.
This bug can happen if a kprobe is put in an instruction which is in the
middle of the jump-replaced instruction sequence of an optprobe, *and* the
optprobe is recently unregistered and queued on unoptimizing_list.
In this case, the optprobe will be unoptimized forcibly (means immediately)
and put it into the freeing_list, expecting the optprobe will be handled in
do_unoptimize_kprobe().
But if there is no other optprobes on the unoptimizing_list, current code
returns from the do_unoptimize_kprobe() soon and does not handle the
optprobe which is on the freeing_list. Then the optprobe will hit the
WARN_ON_ONCE() in the do_free_cleaned_kprobes(), because it is not handled
in the latter loop of the do_unoptimize_kprobe().
To solve this issue, do not return from do_unoptimize_kprobes() immediately
even if unoptimizing_list is empty.
Moreover, this change affects another case. kill_optimized_kprobes() expects
kprobe_optimizer() will just free the optprobe on freeing_list.
So I changed it to just do list_move() to freeing_list if optprobes are on
unoptimizing list. And the do_unoptimize_kprobe() will skip
arch_disarm_kprobe() if the probe on freeing_list has gone flag.
Link: https://lore.kernel.org/all/Y8URdIfVr3pq2X8w@xxxxxxxxxxxxxxxx/
Link: https://lore.kernel.org/all/167448024501.3253718.13037333683110512967.stgit@devnote3/
Fixes: e4add247789e ("kprobes: Fix optimize_kprobe()/unoptimize_kprobe() cancellation logic")
Reported-by: Pengfei Xu <pengfei.xu@xxxxxxxxx>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Acked-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
[fp: adjust comment conflict regarding commit 223a76b268c9 ("kprobes: Fix
coding style issues")]
Signed-off-by: Fedor Pchelkin <pchelkin@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/kprobes.c | 23 ++++++++++-------------
1 file changed, 10 insertions(+), 13 deletions(-)
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -549,17 +549,15 @@ static void do_unoptimize_kprobes(void)
/* See comment in do_optimize_kprobes() */
lockdep_assert_cpus_held();
- /* Unoptimization must be done anytime */
- if (list_empty(&unoptimizing_list))
- return;
+ if (!list_empty(&unoptimizing_list))
+ arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list);
- arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list);
- /* Loop free_list for disarming */
+ /* Loop on 'freeing_list' for disarming and removing from kprobe hash list */
list_for_each_entry_safe(op, tmp, &freeing_list, list) {
/* Switching from detour code to origin */
op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
- /* Disarm probes if marked disabled */
- if (kprobe_disabled(&op->kp))
+ /* Disarm probes if marked disabled and not gone */
+ if (kprobe_disabled(&op->kp) && !kprobe_gone(&op->kp))
arch_disarm_kprobe(&op->kp);
if (kprobe_unused(&op->kp)) {
/*
@@ -788,14 +786,13 @@ static void kill_optimized_kprobe(struct
op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
if (kprobe_unused(p)) {
- /* Enqueue if it is unused */
- list_add(&op->list, &freeing_list);
/*
- * Remove unused probes from the hash list. After waiting
- * for synchronization, this probe is reclaimed.
- * (reclaiming is done by do_free_cleaned_kprobes().)
+ * Unused kprobe is on unoptimizing or freeing list. We move it
+ * to freeing_list and let the kprobe_optimizer() remove it from
+ * the kprobe hash list and free it.
*/
- hlist_del_rcu(&op->kp.hlist);
+ if (optprobe_queued_unopt(op))
+ list_move(&op->list, &freeing_list);
}
/* Don't touch the code, because it is already freed. */
Patches currently in stable-queue which might be from mhiramat@xxxxxxxxxx are
queue-5.15/kprobes-fix-to-handle-forcibly-unoptimized-kprobes-on-freeing_list.patch
queue-5.15/tracing-have-large-events-show-up-as-line-too-big-in.patch
queue-5.15/ring-buffer-do-not-record-in-nmi-if-the-arch-does-no.patch
queue-5.15/tracing-add-size-check-when-printing-trace_marker-ou.patch
