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Message-Id: <20230615115236.3476617-1-jolsa@kernel.org>
Date: Thu, 15 Jun 2023 13:52:36 +0200
From: Jiri Olsa <jolsa@...nel.org>
To: Steven Rostedt <rostedt@...dmis.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
Mark Rutland <mark.rutland@....com>
Cc: lkml <linux-kernel@...r.kernel.org>,
linux-trace-kernel@...r.kernel.org, bpf@...r.kernel.org
Subject: [PATCH] fprobe: Release rethook after the ftrace_ops is unregistered
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.
Fixes: 5b0ab78998e3 ("fprobe: Add exit_handler support")
Reviewed-by: Steven Rostedt (Google) <rostedt@...dmis.org>
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
kernel/trace/fprobe.c | 12 +++---------
1 file changed, 3 insertions(+), 9 deletions(-)
diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index 18d36842faf5..0121e8c0d54e 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -364,19 +364,13 @@ 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;
--
2.40.1
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