From 45af52e7d3b8560f21d139b3759735eead8b1653 Mon Sep 17 00:00:00 2001 From: guoweikang Date: Wed, 20 Nov 2024 13:27:49 +0800 Subject: [PATCH] ftrace: Fix regression with module command in stack_trace_filter When executing the following command: # echo "write*:mod:ext3" > /sys/kernel/tracing/stack_trace_filter The current mod command causes a null pointer dereference. While commit 0f17976568b3f ("ftrace: Fix regression with module command in stack_trace_filter") has addressed part of the issue, it left a corner case unhandled, which still results in a kernel crash. Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Link: https://lore.kernel.org/20241120052750.275463-1-guoweikang.kernel@gmail.com Fixes: 04ec7bb642b77 ("tracing: Have the trace_array hold the list of registered func probes"); Signed-off-by: guoweikang Signed-off-by: Steven Rostedt (Google) --- kernel/trace/ftrace.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 4c28dd177ca6..5ff0822342ac 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -5076,6 +5076,9 @@ ftrace_mod_callback(struct trace_array *tr, struct ftrace_hash *hash, char *func; int ret; + if (!tr) + return -ENODEV; + /* match_records() modifies func, and we need the original */ func = kstrdup(func_orig, GFP_KERNEL); if (!func)