From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, stable@kernel.org, Masami Hiramatsu , "Steven Rostedt (VMware)" Subject: [PATCH 4.19 115/139] function_graph: Reverse the order of pushing the ret_stack and the callback Date: Tue, 4 Dec 2018 11:49:56 +0100 Message-Id: <20181204103655.349825042@linuxfoundation.org> In-Reply-To: <20181204103649.950154335@linuxfoundation.org> References: <20181204103649.950154335@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Steven Rostedt (VMware) commit 7c6ea35ef50810aa12ab26f21cb858d980881576 upstream. The function graph profiler uses the ret_stack to store the "subtime" and reuse it by nested functions and also on the return. But the current logic has the profiler callback called before the ret_stack is updated, and it is just modifying the ret_stack that will later be allocated (it's just lucky that the "subtime" is not touched when it is allocated). This could also cause a crash if we are at the end of the ret_stack when this happens. By reversing the order of the allocating the ret_stack and then calling the callbacks attached to a function being traced, the ret_stack entry is no longer used before it is allocated. Cc: stable@kernel.org Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback") Reviewed-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace_functions_graph.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -188,15 +188,17 @@ int function_graph_enter(unsigned long r trace.func = func; trace.depth = ++current->curr_ret_depth; - /* Only trace if the calling function expects to */ - if (!ftrace_graph_entry(&trace)) - goto out; - if (ftrace_push_return_trace(ret, func, frame_pointer, retp)) goto out; + /* Only trace if the calling function expects to */ + if (!ftrace_graph_entry(&trace)) + goto out_ret; + return 0; + out_ret: + current->curr_ret_stack--; out: current->curr_ret_depth--; return -EBUSY;