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author | Masami Hiramatsu (Google) <mhiramat@kernel.org> | 2023-07-07 23:03:19 +0900 |
---|---|---|
committer | Masami Hiramatsu (Google) <mhiramat@kernel.org> | 2023-07-11 09:17:01 +0900 |
commit | 195b9cb5b288fec1c871ef89f78cc9a7461aad3a (patch) | |
tree | e2e4739f378177d8a1dfd5e37708c062b2d5384c /kernel/trace/fprobe.c | |
parent | ed9492dfef8738ca68879f5690dda5a04f1897dc (diff) | |
download | linux-stable-195b9cb5b288fec1c871ef89f78cc9a7461aad3a.tar.gz linux-stable-195b9cb5b288fec1c871ef89f78cc9a7461aad3a.tar.bz2 linux-stable-195b9cb5b288fec1c871ef89f78cc9a7461aad3a.zip |
fprobe: Ensure running fprobe_exit_handler() finished before calling rethook_free()
Ensure running fprobe_exit_handler() has finished before
calling rethook_free() in the unregister_fprobe() so that caller can free
the fprobe right after unregister_fprobe().
unregister_fprobe() ensured that all running fprobe_entry/exit_handler()
have finished by calling unregister_ftrace_function() which synchronizes
RCU. But commit 5f81018753df ("fprobe: Release rethook after the ftrace_ops
is unregistered") changed to call rethook_free() after
unregister_ftrace_function(). So call rethook_stop() to make rethook
disabled before unregister_ftrace_function() and ensure it again.
Here is the possible code flow that can call the exit handler after
unregister_fprobe().
------
CPU1 CPU2
call unregister_fprobe(fp)
...
__fprobe_handler()
rethook_hook() on probed function
unregister_ftrace_function()
return from probed function
rethook hooks
find rh->handler == fprobe_exit_handler
call fprobe_exit_handler()
rethook_free():
set rh->handler = NULL;
return from unreigster_fprobe;
call fp->exit_handler() <- (*)
------
(*) At this point, the exit handler is called after returning from
unregister_fprobe().
This fixes it as following;
------
CPU1 CPU2
call unregister_fprobe()
...
rethook_stop():
set rh->handler = NULL;
__fprobe_handler()
rethook_hook() on probed function
unregister_ftrace_function()
return from probed function
rethook hooks
find rh->handler == NULL
return from rethook
rethook_free()
return from unreigster_fprobe;
------
Link: https://lore.kernel.org/all/168873859949.156157.13039240432299335849.stgit@devnote2/
Fixes: 5f81018753df ("fprobe: Release rethook after the ftrace_ops is unregistered")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/fprobe.c')
-rw-r--r-- | kernel/trace/fprobe.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c index 58e4b3607aef..2571f7f3d5f2 100644 --- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -366,6 +366,9 @@ int unregister_fprobe(struct fprobe *fp) fp->ops.saved_func != fprobe_kprobe_handler)) return -EINVAL; + if (fp->rethook) + rethook_stop(fp->rethook); + ret = unregister_ftrace_function(&fp->ops); if (ret < 0) return ret; |