[bug report] fs/ntfs3: Add NTFS journal

[Dan Carpenter <dan.carpenter@xxxxxxxxxx>]

Hello Konstantin Komarov,

Commit b46acd6a6a62 ("fs/ntfs3: Add NTFS journal") from Aug 13, 2021
(linux-next), leads to the following Smatch static checker warning:

	fs/ntfs3/fslog.c:627 enum_rstbl()
	error: we previously assumed 't' could be null (see line 616)

fs/ntfs3/fslog.c
    612 static inline void *enum_rstbl(struct RESTART_TABLE *t, void *c)
    613 {
    614         __le32 *e;
    615         u32 bprt;
    616         u16 rsize = t ? le16_to_cpu(t->size) : 0;
                            ^
If t is NULL this function will either return NULL or crash.  Can t be NULL?
If so, why not add a check for that at the beginning?

	if (!t)
		return NULL;

	rsize = le16_to_cpu(t->size);

    617 
    618         if (!c) {
    619                 if (!t || !t->total)
    620                         return NULL;
    621                 e = Add2Ptr(t, sizeof(struct RESTART_TABLE));
    622         } else {
    623                 e = Add2Ptr(c, rsize);
    624         }
    625 
    626         /* Loop until we hit the first one allocated, or the end of the list. */
--> 627         for (bprt = bytes_per_rt(t); PtrOffset(t, e) < bprt;
                                         ^
NULL dereference

    628              e = Add2Ptr(e, rsize)) {
    629                 if (*e == RESTART_ENTRY_ALLOCATED_LE)
    630                         return e;
    631         }
    632         return NULL;
    633 }

regards,
dan carpenter