Messages in this thread Patch in this message | | | From | Levi Yun <> | Subject | [PATCH] kprobe: sync issue's on ftraced-kprobe. | Date | Mon, 2 May 2022 13:51:02 +0900 |
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In kprobe_ftrace_handler, it accesses get kporbe without kprobe_mutex held.
This makes some of synchronizing issue when we use kprobe API in kernel-module.
Below is what i experienced:
CPU 0 CPU 1 <...> <In module code> kprobe_ftrace_handler get_kprobe __this_cpu_write unregister_kprobe unload_module < kprobe memory gone> p->pre_handler <access invalid memory> page_fault kprobe_fault_handler (In here, kprobe memory gone, double page fault is happening inifinie).
Signed-off-by: Levi Yun <ppbuk5246@gmail.com> --- arch/x86/kernel/kprobes/ftrace.c | 3 +++ include/linux/kprobes.h | 2 ++ kernel/kprobes.c | 2 +- 3 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/kprobes/ftrace.c b/arch/x86/kernel/kprobes/ftrace.c index dd2ec14adb77..76147ff6ed88 100644 --- a/arch/x86/kernel/kprobes/ftrace.c +++ b/arch/x86/kernel/kprobes/ftrace.c @@ -25,6 +25,7 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, if (bit < 0) return; + mutex_lock(&kprobe_mutex); p = get_kprobe((kprobe_opcode_t *)ip); if (unlikely(!p) || kprobe_disabled(p)) goto out; @@ -57,7 +58,9 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, */ __this_cpu_write(current_kprobe, NULL); } + out: + mutex_unlock(&kprobe_mutex); ftrace_test_recursion_unlock(bit); } NOKPROBE_SYMBOL(kprobe_ftrace_handler); diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h index 157168769fc2..4a18147ff6d6 100644 --- a/include/linux/kprobes.h +++ b/include/linux/kprobes.h @@ -191,6 +191,8 @@ struct kprobe_blacklist_entry { DECLARE_PER_CPU(struct kprobe *, current_kprobe); DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); +extern struct mutex kprobe_mutex; + extern void kprobe_busy_begin(void); extern void kprobe_busy_end(void); diff --git a/kernel/kprobes.c b/kernel/kprobes.c index dd58c0be9ce2..b65f055b6fa2 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -64,7 +64,7 @@ static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; static bool kprobes_all_disarmed; /* This protects 'kprobe_table' and 'optimizing_list' */ -static DEFINE_MUTEX(kprobe_mutex); +DEFINE_MUTEX(kprobe_mutex); static DEFINE_PER_CPU(struct kprobe *, kprobe_instance); kprobe_opcode_t * __weak kprobe_lookup_name(const char *name, -- 2.35.1
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