This is a note to let you know that I've just added the patch titled
fprobe: Release rethook after the ftrace_ops is unregistered
to the 6.4-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:
fprobe-release-rethook-after-the-ftrace_ops-is-unregistered.patch
and it can be found in the queue-6.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 5f81018753dfd4989e33ece1f0cb6b8aae498b82 Mon Sep 17 00:00:00 2001
From: Jiri Olsa <jolsa@xxxxxxxxxx>
Date: Thu, 15 Jun 2023 13:52:36 +0200
Subject: fprobe: Release rethook after the ftrace_ops is unregistered
From: Jiri Olsa <jolsa@xxxxxxxxxx>
commit 5f81018753dfd4989e33ece1f0cb6b8aae498b82 upstream.
While running bpf selftests it's possible to get following fault:
general protection fault, probably for non-canonical address \
0x6b6b6b6b6b6b6b6b: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
...
Call Trace:
<TASK>
fprobe_handler+0xc1/0x270
? __pfx_bpf_testmod_init+0x10/0x10
? __pfx_bpf_testmod_init+0x10/0x10
? bpf_fentry_test1+0x5/0x10
? bpf_fentry_test1+0x5/0x10
? bpf_testmod_init+0x22/0x80
? do_one_initcall+0x63/0x2e0
? rcu_is_watching+0xd/0x40
? kmalloc_trace+0xaf/0xc0
? do_init_module+0x60/0x250
? __do_sys_finit_module+0xac/0x120
? do_syscall_64+0x37/0x90
? entry_SYSCALL_64_after_hwframe+0x72/0xdc
</TASK>
In unregister_fprobe function we can't release fp->rethook while it's
possible there are some of its users still running on another cpu.
Moving rethook_free call after fp->ops is unregistered with
unregister_ftrace_function call.
Link: https://lore.kernel.org/all/20230615115236.3476617-1-jolsa@xxxxxxxxxx/
Fixes: 5b0ab78998e3 ("fprobe: Add exit_handler support")
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/trace/fprobe.c | 12 +++---------
1 file changed, 3 insertions(+), 9 deletions(-)
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -366,19 +366,13 @@ int unregister_fprobe(struct fprobe *fp)
fp->ops.saved_func != fprobe_kprobe_handler))
return -EINVAL;
- /*
- * rethook_free() starts disabling the rethook, but the rethook handlers
- * may be running on other processors at this point. To make sure that all
- * current running handlers are finished, call unregister_ftrace_function()
- * after this.
- */
- if (fp->rethook)
- rethook_free(fp->rethook);
-
ret = unregister_ftrace_function(&fp->ops);
if (ret < 0)
return ret;
+ if (fp->rethook)
+ rethook_free(fp->rethook);
+
ftrace_free_filter(&fp->ops);
return ret;
Patches currently in stable-queue which might be from jolsa@xxxxxxxxxx are
queue-6.4/fprobe-release-rethook-after-the-ftrace_ops-is-unregistered.patch
