diff_cb() does not handle large dnodes

Trying to 'zfs diff' a snapshot with large dnodes will incorrectly try to access its interior slots when dnodesize > sizeof(dnode_phys_t). This is normally not an issue because the interior slots are zero-filled, which report_dnode() handles calling report_free_dnode_range(). However this is not the case for encrypted large dnodes or filesystem using many SA based xattrs where the extra data past the legacy dnode size boundary is interpreted as a dnode_phys_t. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Tom Caputi <[email protected]> Reviewed-by: Ryan Moeller <[email protected]> Signed-off-by: loli10K <[email protected]> Closes openzfs#7678 Closes openzfs#8931 Closes openzfs#9343
tonyhutter · Dec 27, 2019 · 484a9d4 · 484a9d4
1 parent 49f7f24
commit 484a9d4
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diff --git a/module/zfs/dmu_diff.c b/module/zfs/dmu_diff.c
@@ -21,6 +21,7 @@
 /*
  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
+ * Copyright (c) 2019, loli10K <[email protected]>. All rights reserved.
  */
 
 #include <sys/dmu.h>
@@ -130,7 +131,7 @@ diff_cb(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
 		dnode_phys_t *blk;
 		arc_buf_t *abuf;
 		arc_flags_t aflags = ARC_FLAG_WAIT;
-		int blksz = BP_GET_LSIZE(bp);
+		int epb = BP_GET_LSIZE(bp) >> DNODE_SHIFT;
 		int zio_flags = ZIO_FLAG_CANFAIL;
 		int i;
 
@@ -142,7 +143,7 @@ diff_cb(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
 			return (SET_ERROR(EIO));
 
 		blk = abuf->b_data;
-		for (i = 0; i < blksz >> DNODE_SHIFT; i++) {
+		for (i = 0; i < epb; i += blk[i].dn_extra_slots + 1) {
 			uint64_t dnobj = (zb->zb_blkid <<
 			    (DNODE_BLOCK_SHIFT - DNODE_SHIFT)) + i;
 			err = report_dnode(da, dnobj, blk+i);

diff --git a/tests/zfs-tests/tests/functional/cli_root/zfs_diff/zfs_diff_encrypted.ksh b/tests/zfs-tests/tests/functional/cli_root/zfs_diff/zfs_diff_encrypted.ksh
@@ -24,14 +24,15 @@
 # 1. Create an encrypted dataset
 # 2. Create two snapshots of the dataset
 # 3. Perform 'zfs diff -Ft' and verify no errors occur
+# 4. Perform the same test on a dataset with large dnodes
 #
 
 verify_runnable "both"
 
 function cleanup
 {
-	datasetexists $TESTPOOL/$TESTFS1 && \
-		log_must zfs destroy -r $TESTPOOL/$TESTFS1
+	destroy_dataset "$TESTPOOL/$TESTFS1" "-r"
+	destroy_dataset "$TESTPOOL/$TESTFS2" "-r"
 }
 
 log_assert "'zfs diff' should work with encrypted datasets"
@@ -50,4 +51,13 @@ log_must zfs snapshot $TESTPOOL/$TESTFS1@snap2
 # 3. Perform 'zfs diff' and verify no errors occur
 log_must zfs diff -Ft $TESTPOOL/$TESTFS1@snap1 $TESTPOOL/$TESTFS1@snap2
 
+# 4. Perform the same test on a dataset with large dnodes
+log_must eval "echo 'password' | zfs create -o dnodesize=4k \
+	-o encryption=on -o keyformat=passphrase $TESTPOOL/$TESTFS2"
+MNTPOINT="$(get_prop mountpoint $TESTPOOL/$TESTFS2)"
+log_must zfs snapshot $TESTPOOL/$TESTFS2@snap1
+log_must touch "$MNTPOINT/file"
+log_must zfs snapshot $TESTPOOL/$TESTFS2@snap2
+log_must zfs diff -Ft $TESTPOOL/$TESTFS2@snap1 $TESTPOOL/$TESTFS2@snap2
+
 log_pass "'zfs diff' works with encrypted datasets"