[LU-18106] conf-sanity test 91: fails to evict large NIDs

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.16.0
• Severity: 3
• Assignee: Chris Horn
• Reporter: Chris Horn

Description

lprocfs_mds_evict_client_seq_write/lprocfs_evict_client_seq_write use UUID_MAX to determine the number of bytes to copy from userspace, but large NIDs can exceed this size.

#define BUFLEN (UUID_MAX + 4)

static ssize_t
lprocfs_mds_evict_client_seq_write(struct file *file, const char __user *buf,
                                   size_t count, loff_t *off)
{
        struct seq_file   *m = file->private_data;
        struct obd_device *obd = m->private;
        struct mdt_device *mdt = mdt_dev(obd->obd_lu_dev);
        char *kbuf;
        char *tmpbuf;
        int rc = 0;

        OBD_ALLOC(kbuf, BUFLEN);
        if (kbuf == NULL)
                return -ENOMEM;

        /*
         * OBD_ALLOC() will zero kbuf, but we only copy BUFLEN - 1
         * bytes into kbuf, to ensure that the string is NUL-terminated.
         * UUID_MAX should include a trailing NUL already.
         */
        if (copy_from_user(kbuf, buf, min_t(unsigned long, BUFLEN - 1, count)))
                GOTO(out, rc = -EFAULT);

LNet NIDs can be up to LNET_NIDSTR_SIZE (64) bytes, so a large NID will get truncated, no matching export found, and thus no eviction.

Issue Links

• is duplicated by: LU-18209 conf-sanity test 91: fails to evict large NIDs