File System Service - Illegal Memory Access

[htcrane]

TL;DR: FATFS_stat & FATFS_readdir of the file system interface make illegal memory accesses to a character array never allocated.

When the File System Service is configured to use FatFS, the SYS_FS_FileStat interface attempts an illegal memory access that causes a bus fault (specifically an imprecise bus error). This occurs due to char* lfname of the SYS_FS_FSTAT struct is not used according to documentation, but the sys_fs_fat_interface.c dereferences this uninitialized pointer and assigns a value to a random location. The offending code snippet is provided below. I would recommend setting the pointer to NULL instead fileStat->lfname = NULL as an easy fix.

int FATFS_stat (
    const char* path,   /* Pointer to the file path */
    uintptr_t fileInfo  /* Pointer to file information to return */
)
{
    FRESULT res;
    FILINFO *finfo = (FILINFO *)fileInfo;

    res = f_stat((const TCHAR *)path, finfo);

    if (finfo != NULL)
    {
        SYS_FS_FSTAT *fileStat = (SYS_FS_FSTAT *)fileInfo;

        if ((res == FR_OK) && (fileStat->lfname != NULL))
        {
            /* Use fileStat->fname instead */
            fileStat->lfname[0] = '\0';
        }
    }

    return ((int)res);
}

I see the FATFS_readdir() function in the interface makes similar illegal access as well.

For replication, one should test with calling on a directory or file that already exists. I am using a SAME53 that had this code generated using the latest MCC.

[htcrane]

@vishalnxt, just tagging to notify.

[jigneshmoradiya1]

@htcrane , Thanks for reporting this issue. This issue will be fixed in the upcoming core v3.14.0 release.