[PATCH 1/5] zfs: Fix malloc() success check

[mwleeds at mailtundra.com]

This code was hitting the error code path whenever malloc() succeeded
rather than when it failed, so presumably this part of the code hasn't
been tested. I had to apply this fix (and others) to get U-Boot to boot
from ZFS on an Nvidia Jetson TX2 NX SoM (an aarch64 computer).

Signed-off-by: Phaedrus Leeds <mwleeds at mailtundra.com>
Tested-by: Phaedrus Leeds <mwleeds at mailtundra.com>
---
 fs/zfs/zfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/zfs/zfs.c b/fs/zfs/zfs.c
index 1fec96cd5c..14779dee32 100644
--- a/fs/zfs/zfs.c
+++ b/fs/zfs/zfs.c
@@ -648,21 +648,21 @@ dmu_read(dnode_end_t *dn, uint64_t blkid, void **buf,
 		if (bp_array != dn->dn.dn_blkptr) {
 			free(bp_array);
 			bp_array = 0;
 		}
 
 		if (BP_IS_HOLE(bp)) {
 			size_t size = zfs_to_cpu16(dn->dn.dn_datablkszsec,
 											dn->endian)
 				<< SPA_MINBLOCKSHIFT;
 			*buf = malloc(size);
-			if (*buf) {
+			if (!*buf) {
 				err = ZFS_ERR_OUT_OF_MEMORY;
 				break;
 			}
 			memset(*buf, 0, size);
 			endian = (zfs_to_cpu64(bp->blk_prop, endian) >> 63) & 1;
 			break;
 		}
 		if (level == 0) {
 			err = zio_read(bp, endian, buf, 0, data);
 			endian = (zfs_to_cpu64(bp->blk_prop, endian) >> 63) & 1;
-- 
2.44.0