From bcb53209be5cb32d485507452edda19b78f31d84 Mon Sep 17 00:00:00 2001
From: Masami Hiramatsu <mhiramat@kernel.org>
Date: Tue, 1 Sep 2020 00:12:07 +0900
Subject: [PATCH] kprobes: Fix to check probe enabled before
disarm_kprobe_ftrace()
Git-commit: bcb53209be5cb32d485507452edda19b78f31d84
References: git-fixes
Patch-mainline: v5.10-rc1
Commit:
0cb2f1372baa ("kprobes: Fix NULL pointer dereference at kprobe_ftrace_handler")
fixed one bug but the underlying bugs are not completely fixed yet.
If we run a kprobe_module.tc of ftracetest, a warning triggers:
# ./ftracetest test.d/kprobe/kprobe_module.tc
=== Ftrace unit tests ===
[1] Kprobe dynamic event - probing module
...
------------[ cut here ]------------
Failed to disarm kprobe-ftrace at trace_printk_irq_work+0x0/0x7e [trace_printk] (-2)
WARNING: CPU: 7 PID: 200 at kernel/kprobes.c:1091 __disarm_kprobe_ftrace.isra.0+0x7e/0xa0
This is because the kill_kprobe() calls disarm_kprobe_ftrace() even
if the given probe is not enabled. In that case, ftrace_set_filter_ip()
fails because the given probe point is not registered to ftrace.
Fix to check the given (going) probe is enabled before invoking
disarm_kprobe_ftrace().
Fixes: 0cb2f1372baa ("kprobes: Fix NULL pointer dereference at kprobe_ftrace_handler")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/159888672694.1411785.5987998076694782591.stgit@devnote2
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
kernel/kprobes.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 732a70163584..3b61ae8ff5da 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2235,9 +2235,10 @@ static void kill_kprobe(struct kprobe *p)
/*
* The module is going away. We should disarm the kprobe which
- * is using ftrace.
+ * is using ftrace, because ftrace framework is still available at
+ * MODULE_STATE_GOING notification.
*/
- if (kprobe_ftrace(p))
+ if (kprobe_ftrace(p) && !kprobe_disabled(p) && !kprobes_all_disarmed)
disarm_kprobe_ftrace(p);
}
--
2.26.2