Intel mpx: что вызывает gcc потепление [-Wchkp], если нет связанных операций

Question

Intel mpx - это набор инструкций процессора, которые позволяют проверять границы функций. Если через Intel mpx обнаружено переполнение, выдается сигнал SIGSEV, даже если программа все равно сможет работать, если она была скомпилирована без Intel MPX.

При компиляции libntfs‑3g у меня была эта проблема, которая была подтверждена во время выполнения:

attrib.c: In function ‘ntfs_resident_attr_resize_i.chkp’:
attrib.c:3444:8: warning: memory access check always fail [-Wchkp]
   mrec = ni->mrec;
   ~~~~~^~~~~~~~~~
attrib.c:3444:8: warning: memory access check always fail [-Wchkp]

Проблема в том, что я не вижу, как может быть переполнение буфера через это простое назначение указателя:

/**
 * struct MFT_RECORD - An MFT record layout (NTFS 3.1+)
 *
 * The mft record header present at the beginning of every record in the mft.
 * This is followed by a sequence of variable length attribute records which
 * is terminated by an attribute of type AT_END which is a truncated attribute
 * in that it only consists of the attribute type code AT_END and none of the
 * other members of the attribute structure are present.
 */
typedef struct {
    NTFS_RECORD_TYPES magic;/* Usually the magic is "FILE". */
    le16 usa_ofs;        /* See NTFS_RECORD definition above. */
    le16 usa_count;        /* See NTFS_RECORD definition above. */
/*  8*/    leLSN lsn;        /* $LogFile sequence number for this record.
                   Changed every time the record is modified. */
/* 16*/    le16 sequence_number;    /* Number of times this mft record has been
                   reused. (See description for MFT_REF
                   above.) NOTE: The increment (skipping zero)
                   is done when the file is deleted. NOTE: If
                   this is zero it is left zero. */
/* 18*/    le16 link_count;        /* Number of hard links, i.e. the number of
                   directory entries referencing this record.
                   NOTE: Only used in mft base records.
                   NOTE: When deleting a directory entry we
                   check the link_count and if it is 1 we
                   delete the file. Otherwise we delete the
                   FILE_NAME_ATTR being referenced by the
                   directory entry from the mft record and
                   decrement the link_count.
/* 20*/    le16 attrs_offset;    /* Byte offset to the first attribute in this
                   mft record from the start of the mft record.
                   NOTE: Must be aligned to 8-byte boundary. */
/* 22*/    MFT_RECORD_FLAGS flags;    /* Bit array of MFT_RECORD_FLAGS. When a file
                   is deleted, the MFT_RECORD_IN_USE flag is
                   set to zero. */
/* 24*/    le32 bytes_in_use;    /* Number of bytes used in this mft record.
                   NOTE: Must be aligned to 8-byte boundary. */
/* 28*/    le32 bytes_allocated;    /* Number of bytes allocated for this mft
                   record. This should be equal to the mft
                   record size. */
/* 32*/    leMFT_REF base_mft_record;
/* 40*/    le16 next_attr_instance; /* The instance number that will be
                   assigned to the next attribute added to this
                   mft record. NOTE: Incremented each time
                   after it is used. NOTE: Every time the mft
                   record is reused this number is set to zero.
                   NOTE: The first instance number is always 0.
                 */
/* The below fields are specific to NTFS 3.1+ (Windows XP and above): */
/* 42*/ le16 reserved;        /* Reserved/alignment. */
/* 44*/ le32 mft_record_number;    /* Number of this mft record. */
/* sizeof() = 48 bytes */
} __attribute__((__packed__)) MFT_RECORD;

struct ntfs_attr_search_ctx {
    MFT_RECORD *mrec;
    ATTR_RECORD *attr;
    BOOL is_first;
    ntfs_inode *ntfs_ino;
    ATTR_LIST_ENTRY *al_entry;
    ntfs_inode *base_ntfs_ino;
    MFT_RECORD *base_mrec;
    ATTR_RECORD *base_attr;
};

/**
 * ntfs_attr_init_search_ctx - initialize an attribute search context
 * @ctx:    attribute search context to initialize
 * @ni:     ntfs inode with which to initialize the search context
 * @mrec:   mft record with which to initialize the search context
 *
 * Initialize the attribute search context @ctx with @ni and @mrec.
 */
static void ntfs_attr_init_search_ctx(ntfs_attr_search_ctx *ctx,
        ntfs_inode *ni, MFT_RECORD *mrec)
{
    if (!mrec)
        mrec = ni->mrec; // attrib.c:3444:8: warning: memory access check always fail [-Wchkp]
    ctx->mrec = mrec;

И когда я компилирую libntfs‑3g с помощью libasan, во время выполнения не обнаружено ни потепления, ни переполнения. Это происходит только с NTFS ‑ 3g