commit a1461f1fd6cfdc4b8917c9d4a91e92605d1f28dc upstream.
Since the rethook::handler is an RCU-maganged pointer so that it will
notice readers the rethook is stopped (unregistered) or not, it should
be an __rcu pointer and use appropriate functions to be accessed. This
will use appropriate memory barrier when accessing it. OTOH,
rethook::data is never changed, so we don't need to check it in
get_kretprobe().
NOTE: To avoid sparse warning, rethook::handler is defined by a raw
function pointer type with __rcu instead of rethook_handler_t.
Link: https://lore.kernel.org/all/170126066201.398836.837498688669005979.stgit@devnote2/
Fixes: 54ecbe6f1ed5 ("rethook: Add a generic return hook")
Cc: stable@vger.kernel.org
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311241808.rv9ceuAh-lkp@intel.com/
Tested-by: JP Kobryn <inwardvessel@gmail.com>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 195b9cb5b288fec1c871ef89f78cc9a7461aad3a upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit be243bacfb25f5219f2396d787408e8cf1301dd1 upstream.
This patch replaces preempt_{disable, enable} with its corresponding
notrace version in rethook_trampoline_handler so no worries about stack
recursion or overflow introduced by preempt_count_{add, sub} under
fprobe + rethook context.
Link: https://lore.kernel.org/all/20230517034510.15639-2-zegao@tencent.com/
Fixes: 54ecbe6f1ed5 ("rethook: Add a generic return hook")
Signed-off-by: Ze Gao <zegao@tencent.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In rethook_alloc(), the variable rh is not freed or passed out
if handler is NULL, which could lead to a memleak, fix it.
Link: https://lore.kernel.org/all/20221110104438.88099-1-yiyang13@huawei.com/
[Masami: Add "rethook:" tag to the title.]
Fixes: 54ecbe6f1ed5 ("rethook: Add a generic return hook")
Cc: stable@vger.kernel.org
Signed-off-by: Yi Yang <yiyang13@huawei.com>
Acke-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Since the rethook_recycle() will involve the call_rcu() for reclaiming
the rethook_instance, the rethook must be set up at the RCU available
context (non idle). This rethook_recycle() in the rethook trampoline
handler is inevitable, thus the RCU available check must be done before
setting the rethook trampoline.
This adds a rcu_is_watching() check in the rethook_try_get() so that
it will return NULL if it is called when !rcu_is_watching().
Fixes: 54ecbe6f1ed5 ("rethook: Add a generic return hook")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/165461827269.280167.7379263615545598958.stgit@devnote2
Since the function pointered by rethook::handler never be removed when the rethook is alive, it doesn't need to use rcu_assign_pointer() to update it. Just use WRITE_ONCE(). Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/164868907688.21983.1606862921419988152.stgit@devnote2
Add a return hook framework which hooks the function return. Most of the logic came from the kretprobe, but this is independent from kretprobe. Note that this is expected to be used with other function entry hooking feature, like ftrace, fprobe, adn kprobes. Eventually this will replace the kretprobe (e.g. kprobe + rethook = kretprobe), but at this moment, this is just an additional hook. Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Tested-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/164735285066.1084943.9259661137330166643.stgit@devnote2