[bug report] fs/ntfs3: inconsistent NULL checking in ntfs_read_run_nb()

[bug report] fs/ntfs3: inconsistent NULL checking in ntfs_read_run_nb()

[Dan Carpenter]

Hello Konstantin Komarov,

This is a semi-automatic email about new static checker warnings.

The patch 82cae269cfa9: "fs/ntfs3: Add initialization of super block" 
from Aug 13, 2021, leads to the following Smatch complaint:

    fs/ntfs3/fsntfs.c:1265 ntfs_read_run_nb()
    error: we previously assumed 'run' could be null (see line 1195)

fs/ntfs3/fsntfs.c
  1194	
  1195		if (!run) {
                    ^^^^
"run" is NULL here.

  1196			/* first reading of $Volume + $MFTMirr + LogFile goes here*/
  1197			if (vbo > MFT_REC_VOL * sbi->record_size) {
  1198				err = -ENOENT;
  1199				goto out;
  1200			}
  1201	
  1202			/* use absolute boot's 'MFTCluster' to read record */
  1203			lbo = vbo + sbi->mft.lbo;
  1204			len = sbi->record_size;
  1205		} else if (!run_lookup_entry(run, vcn, &lcn, &clen, &idx)) {
  1206			err = -ENOENT;
  1207			goto out;
  1208		} else {
  1209			if (lcn == SPARSE_LCN) {
  1210				err = -EINVAL;
  1211				goto out;
  1212			}
  1213	
  1214			lbo = ((u64)lcn << cluster_bits) + off;
  1215			len = ((u64)clen << cluster_bits) - off;
  1216		}
  1217	
  1218		off = lbo & (blocksize - 1);
  1219		if (nb) {
  1220			nb->off = off;
  1221			nb->bytes = bytes;
  1222		}
  1223	
  1224		for (;;) {
  1225			u32 len32 = len >= bytes ? bytes : len;
  1226			sector_t block = lbo >> sb->s_blocksize_bits;
  1227	
  1228			do {
  1229				u32 op = blocksize - off;
  1230	
  1231				if (op > len32)
  1232					op = len32;
  1233	
  1234				bh = ntfs_bread(sb, block);
  1235				if (!bh) {
  1236					err = -EIO;
  1237					goto out;
  1238				}
  1239	
  1240				if (buf) {
  1241					memcpy(buf, bh->b_data + off, op);
  1242					buf = Add2Ptr(buf, op);
  1243				}
  1244	
  1245				if (!nb) {
  1246					put_bh(bh);
  1247				} else if (nbh >= ARRAY_SIZE(nb->bh)) {
  1248					err = -EINVAL;
  1249					goto out;
  1250				} else {
  1251					nb->bh[nbh++] = bh;
  1252					nb->nbufs = nbh;
  1253				}
  1254	
  1255				bytes -= op;
  1256				if (!bytes)
  1257					return 0;
  1258				len32 -= op;
  1259				block += 1;
  1260				off = 0;
  1261	
  1262			} while (len32);
  1263	
  1264			vcn_next = vcn + clen;
  1265			if (!run_get_entry(run, ++idx, &vcn, &lcn, &clen) ||
                                           ^^^
Uchecked dereference.

  1266			    vcn != vcn_next) {
  1267				err = -ENOENT;

regards,
dan carpenter