From cc72b72073ac982a954d3b43519ca1c28f03c27c Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Sat, 28 May 2022 00:55:39 +0900 Subject: tracing/kprobes: Check whether get_kretprobe() returns NULL in kretprobe_dispatcher() There is a small chance that get_kretprobe(ri) returns NULL in kretprobe_dispatcher() when another CPU unregisters the kretprobe right after __kretprobe_trampoline_handler(). To avoid this issue, kretprobe_dispatcher() checks the get_kretprobe() return value again. And if it is NULL, it returns soon because that kretprobe is under unregistering process. This issue has been introduced when the kretprobe is decoupled from the struct kretprobe_instance by commit d741bf41d7c7 ("kprobes: Remove kretprobe hash"). Before that commit, the struct kretprob_instance::rp directly points the kretprobe and it is never be NULL. Link: https://lkml.kernel.org/r/165366693881.797669.16926184644089588731.stgit@devnote2 Reported-by: Yonghong Song Fixes: d741bf41d7c7 ("kprobes: Remove kretprobe hash") Cc: Peter Zijlstra Cc: Ingo Molnar Cc: bpf Cc: Kernel Team Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu (Google) Acked-by: Jiri Olsa Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_kprobe.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 93507330462c..a245ea673715 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -1718,8 +1718,17 @@ static int kretprobe_dispatcher(struct kretprobe_instance *ri, struct pt_regs *regs) { struct kretprobe *rp = get_kretprobe(ri); - struct trace_kprobe *tk = container_of(rp, struct trace_kprobe, rp); + struct trace_kprobe *tk; + + /* + * There is a small chance that get_kretprobe(ri) returns NULL when + * the kretprobe is unregister on another CPU between kretprobe's + * trampoline_handler and this function. + */ + if (unlikely(!rp)) + return 0; + tk = container_of(rp, struct trace_kprobe, rp); raw_cpu_inc(*tk->nhit); if (trace_probe_test_flag(&tk->tp, TP_FLAG_TRACE)) -- cgit v1.2.3 From f4b0d318097e45cbac5e14976f8bb56aa2cef504 Mon Sep 17 00:00:00 2001 From: sunliming Date: Thu, 2 Jun 2022 22:06:13 +0800 Subject: tracing: Simplify conditional compilation code in tracing_set_tracer() Two conditional compilation directives "#ifdef CONFIG_TRACER_MAX_TRACE" are used consecutively, and no other code in between. Simplify conditional the compilation code and only use one "#ifdef CONFIG_TRACER_MAX_TRACE". Link: https://lkml.kernel.org/r/20220602140613.545069-1-sunliming@kylinos.cn Signed-off-by: sunliming Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 2c95992e2c71..a8cfac0611bc 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6424,9 +6424,7 @@ int tracing_set_tracer(struct trace_array *tr, const char *buf) synchronize_rcu(); free_snapshot(tr); } -#endif -#ifdef CONFIG_TRACER_MAX_TRACE if (t->use_max_tr && !had_max_tr) { ret = tracing_alloc_snapshot_instance(tr); if (ret < 0) -- cgit v1.2.3 From 12c3e0c92fd7cb3d3b698d84fdde7dccb6ba8822 Mon Sep 17 00:00:00 2001 From: Gautam Menghani Date: Sun, 12 Jun 2022 07:42:32 -0700 Subject: tracing/uprobes: Remove unwanted initialization in __trace_uprobe_create() Remove the unwanted initialization of variable 'ret'. This fixes the clang scan warning: Value stored to 'ret' is never read [deadcode.DeadStores] Link: https://lkml.kernel.org/r/20220612144232.145209-1-gautammenghani201@gmail.com Signed-off-by: Gautam Menghani Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_uprobe.c | 1 - 1 file changed, 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c index 9711589273cd..c3dc4f859a6b 100644 --- a/kernel/trace/trace_uprobe.c +++ b/kernel/trace/trace_uprobe.c @@ -546,7 +546,6 @@ static int __trace_uprobe_create(int argc, const char **argv) bool is_return = false; int i, ret; - ret = 0; ref_ctr_offset = 0; switch (argv[0][0]) { -- cgit v1.2.3