Commit 2a2d8c51 authored by Zheng Yejian's avatar Zheng Yejian Committed by Steven Rostedt (Google)
Browse files

ftrace: Fix issue that 'direct->addr' not restored in modify_ftrace_direct() 

Syzkaller report a WARNING: "WARN_ON(!direct)" in modify_ftrace_direct().

Root cause is 'direct->addr' was changed from 'old_addr' to 'new_addr' but
not restored if error happened on calling ftrace_modify_direct_caller().
Then it can no longer find 'direct' by that 'old_addr'.

To fix it, restore 'direct->addr' to 'old_addr' explicitly in error path.

Link: https://lore.kernel.org/linux-trace-kernel/20230330025223.1046087-1-zhengyejian1@huawei.com



Cc: stable@vger.kernel.org
Cc: <mhiramat@kernel.org>
Cc: <mark.rutland@arm.com>
Cc: <ast@kernel.org>
Cc: <daniel@iogearbox.net>
Fixes: 8a141dd7 ("ftrace: Fix modify_ftrace_direct.")
Signed-off-by: default avatarZheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 3357c6e4

kernel/trace/ftrace.c

+9 −6
Original line number Diff line number Diff line
@@ -5667,13 +5667,16 @@ int modify_ftrace_direct(unsigned long ip, 
		ret = 0;

	}



	if (unlikely(ret && new_direct)) {

	if (ret) {

		direct->addr = old_addr;

		if (unlikely(new_direct)) {

			direct->count++;

			list_del_rcu(&new_direct->next);

			synchronize_rcu_tasks();

			kfree(new_direct);

			ftrace_direct_func_count--;

		}

	}



 out_unlock:

	mutex_unlock(&ftrace_lock);