[Bug] Pointer error in rt_vsnprintf function

[LecterChu]

RT-Thread Version

5.2.0 commit 2f55990

Hardware Type/Architectures

VEXPRESS_A9

Develop Toolchain

GCC

Describe the bug

I encountered another error in rt_vsnprintf function.

Steps to reproduce

1.Build RT-Thread
2.Use the following command to start the kernel with QEMU:

qemu-system-arm \
    -M vexpress-a9 \
    -smp 2 \
    -m 4096M \
    -kernel /path/to/rt-thread/bsp/qemu-vexpress-a9/rtthread.bin \
    -drive if=sd,file=/path/to/rt-thread/bsp/qemu-vexpress-a9/sd.bin,format=raw \
    -nographic \
    -semihosting \

3.Use the functions and parameters provided in the ’Test case‘ section for testing

Source code location

/root/rtthread/rt-thread/src/klibc/kstdio.c : 337

        /* Make sure end is always >= buf */
        if (end < buf)
        {
            end  = ((char *) - 1);
            size = end - buf;
        }

        for (; *fmt ; ++fmt)
        {
337:        if (*fmt != '%')
        {
                if (str < end)
                {
                    *str = *fmt;
                }

Test case

#executing syz_thread_idle_init ()

void syz_thread_idle_init() {
    if (rt_thread_idle_gethandler() != RT_NULL) {
        rt_kprintf("Idle thread is already initialized.\n");
        return; 
    }
    rt_thread_idle_init();
}

Backtrace upon hitting the bug

#executing syz_thread_idle_init ()
2024/09/04 12:18:37 Syscall execution is ok
2024/09/04 12:18:37 qemu run inst merger err: execution timed out
2024/09/04 12:18:37 Received stop signal, requires feedback = true
2024/09/04 12:18:37 running diagnose
2024/09/04 12:18:37 VM-0 failed reading regs: dial tcp 127.0.0.1:28192: connect: connection refused
2024/09/04 12:18:37 VM-0 failed reading regs: dial tcp 127.0.0.1:28192: connect: connection refused
2024/09/04 12:18:37 Stack frames at BUG: unexpected stop:
2024/09/04 12:18:37 Level: 0: 1611238884, /root/kcov.c : write_comp_data : 111 : 
2024/09/04 12:18:37 Level: 1: 1611239238, /root/kcov.c : __sanitizer_cov_trace_const_cmp1 : 167 : 
2024/09/04 12:18:37 Level: 2: 1611457888, /root/rtthread/rt-thread/src/klibc/kstdio.c : rt_vsnprintf : 337 : 
2024/09/04 12:18:37 Level: 3: 1611467024, /root/rtthread/rt-thread/src/kservice.c : rt_kprintf : 343 : 
2024/09/04 12:18:37 Level: 4: 1611213996, /root/rtthread/rt-thread/bsp/qemu-vexpress-a9/applications/common_freertos.h : syz_thread_idle_init : 211 : 

It could possibly be that the memory region pointed to by fmt is invalid or out of bounds.
I would greatly appreciate it if you could kindly inform me of any mistakes in the previous issues.

Other additional context

No response

Other additional context

No response