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

[mwleeds]

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 <mwle...@mailtundra.com>
Tested-by: Phaedrus Leeds <mwle...@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