OpenZFS 6314 - buffer overflow in dsl_dataset_name

Reviewed by: George Wilson <[email protected]>
Reviewed by: Prakash Surya <[email protected]>
Reviewed by: Igor Kozhukhov <[email protected]>
Approved by: Dan McDonald <[email protected]>
Ported-by: Brian Behlendorf <[email protected]>

OpenZFS-issue: https://www.illumos.org/issues/6314
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/d6160ee

5 files changed, 83 insertions, 85 deletions

diff --git a/cmd/zdb/zdb.c b/cmd/zdb/zdb.c
index ee5e21f10..967d74216 100644
--- a/cmd/zdb/zdb.c
+++ b/cmd/zdb/zdb.c
@@ -60,7 +60,6 @@
 #include <sys/ddt.h>
 #include <sys/zfeature.h>
 #include <zfs_comutil.h>
-#undef ZFS_MAXNAMELEN
 #include <libzfs.h>
 
 #define	ZDB_COMPRESS_NAME(idx) ((idx) < ZIO_COMPRESS_FUNCTIONS ?	\
@@ -2005,7 +2004,7 @@ dump_dir(objset_t *os)
 	uint64_t refdbytes, usedobjs, scratch;
 	char numbuf[32];
 	char blkbuf[BP_SPRINTF_LEN + 20];
-	char osname[MAXNAMELEN];
+	char osname[ZFS_MAX_DATASET_NAME_LEN];
 	char *type = "UNKNOWN";
 	int verbosity = dump_opt['d'];
 	int print_header = 1;
@@ -3553,7 +3552,7 @@ find_zpool(char **target, nvlist_t **configp, int dirc, char **dirv)
 	nvlist_t *match = NULL;
 	char *name = NULL;
 	char *sepp = NULL;
-	char sep = 0;
+	char sep = '\0';
 	int count = 0;
 	importargs_t args = { 0 };
 
diff --git a/cmd/zfs/zfs_main.c b/cmd/zfs/zfs_main.c
index 3d20973a2..e8a4421cc 100644
--- a/cmd/zfs/zfs_main.c
+++ b/cmd/zfs/zfs_main.c
@@ -1483,7 +1483,7 @@ get_callback(zfs_handle_t *zhp, void *data)
 	char buf[ZFS_MAXPROPLEN];
 	char rbuf[ZFS_MAXPROPLEN];
 	zprop_source_t sourcetype;
-	char source[ZFS_MAXNAMELEN];
+	char source[ZFS_MAX_DATASET_NAME_LEN];
 	zprop_get_cbdata_t *cbp = data;
 	nvlist_t *user_props = zfs_get_user_props(zhp);
 	zprop_list_t *pl = cbp->cb_proplist;
@@ -1963,7 +1963,7 @@ typedef struct upgrade_cbdata {
 	uint64_t cb_version;
 	boolean_t cb_newer;
 	boolean_t cb_foundone;
-	char cb_lastfs[ZFS_MAXNAMELEN];
+	char cb_lastfs[ZFS_MAX_DATASET_NAME_LEN];
 } upgrade_cbdata_t;
 
 static int
@@ -2412,7 +2412,7 @@ userspace_cb(void *arg, const char *domain, uid_t rid, uint64_t space)
 	if (domain != NULL && domain[0] != '\0') {
 #ifdef HAVE_IDMAP
 		/* SMB */
-		char sid[ZFS_MAXNAMELEN + 32];
+		char sid[MAXNAMELEN + 32];
 		uid_t id;
 		uint64_t classes;
 		int err;
@@ -2546,7 +2546,7 @@ print_us_node(boolean_t scripted, boolean_t parsable, int *fields, int types,
     size_t *width, us_node_t *node)
 {
 	nvlist_t *nvl = node->usn_nvl;
-	char valstr[ZFS_MAXNAMELEN];
+	char valstr[MAXNAMELEN];
 	boolean_t first = B_TRUE;
 	int cfield = 0;
 	int field;
@@ -3417,7 +3417,7 @@ zfs_do_rollback(int argc, char **argv)
 	boolean_t force = B_FALSE;
 	rollback_cbdata_t cb = { 0 };
 	zfs_handle_t *zhp, *snap;
-	char parentname[ZFS_MAXNAMELEN];
+	char parentname[ZFS_MAX_DATASET_NAME_LEN];
 	char *delim;
 
 	/* check options */
@@ -3818,7 +3818,7 @@ zfs_do_send(int argc, char **argv)
 	 */
 	if (strchr(argv[0], '@') == NULL ||
 	    (fromname && strchr(fromname, '#') != NULL)) {
-		char frombuf[ZFS_MAXNAMELEN];
+		char frombuf[ZFS_MAX_DATASET_NAME_LEN];
 		enum lzc_send_flags lzc_flags = 0;
 
 		if (flags.replicate || flags.doall || flags.props ||
@@ -3870,7 +3870,7 @@ zfs_do_send(int argc, char **argv)
 	 * case if they specify the origin.
 	 */
 	if (fromname && (cp = strchr(fromname, '@')) != NULL) {
-		char origin[ZFS_MAXNAMELEN];
+		char origin[ZFS_MAX_DATASET_NAME_LEN];
 		zprop_source_t src;
 
 		(void) zfs_prop_get(zhp, ZFS_PROP_ORIGIN,
@@ -4004,7 +4004,7 @@ zfs_do_receive(int argc, char **argv)
 			usage(B_FALSE);
 		}
 
-		char namebuf[ZFS_MAXNAMELEN];
+		char namebuf[ZFS_MAX_DATASET_NAME_LEN];
 		(void) snprintf(namebuf, sizeof (namebuf),
 		    "%s/%%recv", argv[0]);
 
@@ -4860,7 +4860,7 @@ store_allow_perm(zfs_deleg_who_type_t type, boolean_t local, boolean_t descend,
 {
 	int i;
 	char ld[2] = { '\0', '\0' };
-	char who_buf[ZFS_MAXNAMELEN+32];
+	char who_buf[MAXNAMELEN + 32];
 	char base_type = ZFS_DELEG_WHO_UNKNOWN;
 	char set_type = ZFS_DELEG_WHO_UNKNOWN;
 	nvlist_t *base_nvl = NULL;
@@ -5224,7 +5224,7 @@ static void
 print_fs_perms(fs_perm_set_t *fspset)
 {
 	fs_perm_node_t *node = NULL;
-	char buf[ZFS_MAXNAMELEN+32];
+	char buf[MAXNAMELEN + 32];
 	const char *dsname = buf;
 
 	for (node = uu_list_first(fspset->fsps_list); node != NULL;
@@ -5233,7 +5233,7 @@ print_fs_perms(fs_perm_set_t *fspset)
 		uu_avl_t *uge_avl = node->fspn_fsperm.fsp_uge_avl;
 		int left = 0;
 
-		(void) snprintf(buf, ZFS_MAXNAMELEN+32,
+		(void) snprintf(buf, sizeof (buf),
 		    gettext("---- Permissions on %s "),
 		    node->fspn_fsperm.fsp_name);
 		(void) printf("%s", dsname);
@@ -5430,7 +5430,7 @@ zfs_do_hold_rele_impl(int argc, char **argv, boolean_t holding)
 
 	for (i = 0; i < argc; ++i) {
 		zfs_handle_t *zhp;
-		char parent[ZFS_MAXNAMELEN];
+		char parent[ZFS_MAX_DATASET_NAME_LEN];
 		const char *delim;
 		char *path = argv[i];
 
@@ -5558,7 +5558,7 @@ holds_callback(zfs_handle_t *zhp, void *data)
 	nvlist_t *nvl = NULL;
 	nvpair_t *nvp = NULL;
 	const char *zname = zfs_get_name(zhp);
-	size_t znamelen = strnlen(zname, ZFS_MAXNAMELEN);
+	size_t znamelen = strlen(zname);
 
 	if (cbp->cb_recursive) {
 		const char *snapname;
@@ -5579,7 +5579,7 @@ holds_callback(zfs_handle_t *zhp, void *data)
 
 	while ((nvp = nvlist_next_nvpair(nvl, nvp)) != NULL) {
 		const char *tag = nvpair_name(nvp);
-		size_t taglen = strnlen(tag, MAXNAMELEN);
+		size_t taglen = strlen(tag);
 		if (taglen > cbp->cb_max_taglen)
 			cbp->cb_max_taglen  = taglen;
 	}
@@ -6695,7 +6695,7 @@ zfs_do_diff(int argc, char **argv)
 static int
 zfs_do_bookmark(int argc, char **argv)
 {
-	char snapname[ZFS_MAXNAMELEN];
+	char snapname[ZFS_MAX_DATASET_NAME_LEN];
 	zfs_handle_t *zhp;
 	nvlist_t *nvl;
 	int ret = 0;
diff --git a/cmd/zhack/zhack.c b/cmd/zhack/zhack.c
index eedd17c30..cc4f174c6 100644
--- a/cmd/zhack/zhack.c
+++ b/cmd/zhack/zhack.c
@@ -48,7 +48,6 @@
 #include <sys/zio_compress.h>
 #include <sys/zfeature.h>
 #include <sys/dmu_tx.h>
-#undef ZFS_MAXNAMELEN
 #include <libzfs.h>
 
 extern boolean_t zfeature_checks_disable;
diff --git a/cmd/ztest/ztest.c b/cmd/ztest/ztest.c
index ad15dea1d..2cc410f10 100644
--- a/cmd/ztest/ztest.c
+++ b/cmd/ztest/ztest.c
@@ -145,8 +145,8 @@ typedef struct ztest_shared_hdr {
 static ztest_shared_hdr_t *ztest_shared_hdr;
 
 typedef struct ztest_shared_opts {
-	char zo_pool[MAXNAMELEN];
-	char zo_dir[MAXNAMELEN];
+	char zo_pool[ZFS_MAX_DATASET_NAME_LEN];
+	char zo_dir[ZFS_MAX_DATASET_NAME_LEN];
 	char zo_alt_ztest[MAXNAMELEN];
 	char zo_alt_libpath[MAXNAMELEN];
 	uint64_t zo_vdevs;
@@ -262,7 +262,7 @@ typedef struct ztest_od {
 	uint64_t	od_crdnodesize;
 	uint64_t	od_gen;
 	uint64_t	od_crgen;
-	char		od_name[MAXNAMELEN];
+	char		od_name[ZFS_MAX_DATASET_NAME_LEN];
 } ztest_od_t;
 
 /*
@@ -274,7 +274,7 @@ typedef struct ztest_ds {
 	rwlock_t	zd_zilog_lock;
 	zilog_t		*zd_zilog;
 	ztest_od_t	*zd_od;		/* debugging aid */
-	char		zd_name[MAXNAMELEN];
+	char		zd_name[ZFS_MAX_DATASET_NAME_LEN];
 	kmutex_t	zd_dirobj_lock;
 	rll_t		zd_object_lock[ZTEST_OBJECT_LOCKS];
 	zll_t		zd_range_lock[ZTEST_RANGE_LOCKS];
@@ -3504,7 +3504,7 @@ ztest_objset_destroy_cb(const char *name, void *arg)
 static boolean_t
 ztest_snapshot_create(char *osname, uint64_t id)
 {
-	char snapname[MAXNAMELEN];
+	char snapname[ZFS_MAX_DATASET_NAME_LEN];
 	int error;
 
 	(void) snprintf(snapname, sizeof (snapname), "%llu", (u_longlong_t)id);
@@ -3524,10 +3524,10 @@ ztest_snapshot_create(char *osname, uint64_t id)
 static boolean_t
 ztest_snapshot_destroy(char *osname, uint64_t id)
 {
-	char snapname[MAXNAMELEN];
+	char snapname[ZFS_MAX_DATASET_NAME_LEN];
 	int error;
 
-	(void) snprintf(snapname, MAXNAMELEN, "%s@%llu", osname,
+	(void) snprintf(snapname, sizeof (snapname), "%s@%llu", osname,
 	    (u_longlong_t)id);
 
 	error = dsl_destroy_snapshot(snapname, B_FALSE);
@@ -3544,16 +3544,15 @@ ztest_dmu_objset_create_destroy(ztest_ds_t *zd, uint64_t id)
 	int iters;
 	int error;
 	objset_t *os, *os2;
-	char *name;
+	char name[ZFS_MAX_DATASET_NAME_LEN];
 	zilog_t *zilog;
 	int i;
 
 	zdtmp = umem_alloc(sizeof (ztest_ds_t), UMEM_NOFAIL);
-	name = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
 
 	(void) rw_rdlock(&ztest_name_lock);
 
-	(void) snprintf(name, MAXNAMELEN, "%s/temp_%llu",
+	(void) snprintf(name, sizeof (name), "%s/temp_%llu",
 	    ztest_opts.zo_pool, (u_longlong_t)id);
 
 	/*
@@ -3639,7 +3638,6 @@ ztest_dmu_objset_create_destroy(ztest_ds_t *zd, uint64_t id)
 out:
 	(void) rw_unlock(&ztest_name_lock);
 
-	umem_free(name, MAXNAMELEN);
 	umem_free(zdtmp, sizeof (ztest_ds_t));
 }
 
@@ -3668,22 +3666,22 @@ ztest_dsl_dataset_cleanup(char *osname, uint64_t id)
 	char *snap3name;
 	int error;
 
-	snap1name  = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
-	clone1name = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
-	snap2name  = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
-	clone2name = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
-	snap3name  = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
-
-	(void) snprintf(snap1name, MAXNAMELEN, "%s@s1_%llu",
-	    osname, (u_longlong_t)id);
-	(void) snprintf(clone1name, MAXNAMELEN, "%s/c1_%llu",
-	    osname, (u_longlong_t)id);
-	(void) snprintf(snap2name, MAXNAMELEN, "%s@s2_%llu",
-	    clone1name, (u_longlong_t)id);
-	(void) snprintf(clone2name, MAXNAMELEN, "%s/c2_%llu",
-	    osname, (u_longlong_t)id);
-	(void) snprintf(snap3name, MAXNAMELEN, "%s@s3_%llu",
-	    clone1name, (u_longlong_t)id);
+	snap1name  = umem_alloc(ZFS_MAX_DATASET_NAME_LEN, UMEM_NOFAIL);
+	clone1name = umem_alloc(ZFS_MAX_DATASET_NAME_LEN, UMEM_NOFAIL);
+	snap2name  = umem_alloc(ZFS_MAX_DATASET_NAME_LEN, UMEM_NOFAIL);
+	clone2name = umem_alloc(ZFS_MAX_DATASET_NAME_LEN, UMEM_NOFAIL);
+	snap3name  = umem_alloc(ZFS_MAX_DATASET_NAME_LEN, UMEM_NOFAIL);
+
+	(void) snprintf(snap1name, ZFS_MAX_DATASET_NAME_LEN,
+	    "%s@s1_%llu", osname, (u_longlong_t)id);
+	(void) snprintf(clone1name, ZFS_MAX_DATASET_NAME_LEN,
+	    "%s/c1_%llu", osname, (u_longlong_t)id);
+	(void) snprintf(snap2name, ZFS_MAX_DATASET_NAME_LEN,
+	    "%s@s2_%llu", clone1name, (u_longlong_t)id);
+	(void) snprintf(clone2name, ZFS_MAX_DATASET_NAME_LEN,
+	    "%s/c2_%llu", osname, (u_longlong_t)id);
+	(void) snprintf(snap3name, ZFS_MAX_DATASET_NAME_LEN,
+	    "%s@s3_%llu", clone1name, (u_longlong_t)id);
 
 	error = dsl_destroy_head(clone2name);
 	if (error && error != ENOENT)
@@ -3701,11 +3699,11 @@ ztest_dsl_dataset_cleanup(char *osname, uint64_t id)
 	if (error && error != ENOENT)
 		fatal(0, "dsl_destroy_snapshot(%s) = %d", snap1name, error);
 
-	umem_free(snap1name, MAXNAMELEN);
-	umem_free(clone1name, MAXNAMELEN);
-	umem_free(snap2name, MAXNAMELEN);
-	umem_free(clone2name, MAXNAMELEN);
-	umem_free(snap3name, MAXNAMELEN);
+	umem_free(snap1name, ZFS_MAX_DATASET_NAME_LEN);
+	umem_free(clone1name, ZFS_MAX_DATASET_NAME_LEN);
+	umem_free(snap2name, ZFS_MAX_DATASET_NAME_LEN);
+	umem_free(clone2name, ZFS_MAX_DATASET_NAME_LEN);
+	umem_free(snap3name, ZFS_MAX_DATASET_NAME_LEN);
 }
 
 /*
@@ -3723,26 +3721,26 @@ ztest_dsl_dataset_promote_busy(ztest_ds_t *zd, uint64_t id)
 	char *osname = zd->zd_name;
 	int error;
 
-	snap1name  = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
-	clone1name = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
-	snap2name  = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
-	clone2name = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
-	snap3name  = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
+	snap1name  = umem_alloc(ZFS_MAX_DATASET_NAME_LEN, UMEM_NOFAIL);
+	clone1name = umem_alloc(ZFS_MAX_DATASET_NAME_LEN, UMEM_NOFAIL);
+	snap2name  = umem_alloc(ZFS_MAX_DATASET_NAME_LEN, UMEM_NOFAIL);
+	clone2name = umem_alloc(ZFS_MAX_DATASET_NAME_LEN, UMEM_NOFAIL);
+	snap3name  = umem_alloc(ZFS_MAX_DATASET_NAME_LEN, UMEM_NOFAIL);
 
 	(void) rw_rdlock(&ztest_name_lock);
 
 	ztest_dsl_dataset_cleanup(osname, id);
 
-	(void) snprintf(snap1name, MAXNAMELEN, "%s@s1_%llu",
-	    osname, (u_longlong_t)id);
-	(void) snprintf(clone1name, MAXNAMELEN, "%s/c1_%llu",
-	    osname, (u_longlong_t)id);
-	(void) snprintf(snap2name, MAXNAMELEN, "%s@s2_%llu",
-	    clone1name, (u_longlong_t)id);
-	(void) snprintf(clone2name, MAXNAMELEN, "%s/c2_%llu",
-	    osname, (u_longlong_t)id);
-	(void) snprintf(snap3name, MAXNAMELEN, "%s@s3_%llu",
-	    clone1name, (u_longlong_t)id);
+	(void) snprintf(snap1name, ZFS_MAX_DATASET_NAME_LEN,
+	    "%s@s1_%llu", osname, (u_longlong_t)id);
+	(void) snprintf(clone1name, ZFS_MAX_DATASET_NAME_LEN,
+	    "%s/c1_%llu", osname, (u_longlong_t)id);
+	(void) snprintf(snap2name, ZFS_MAX_DATASET_NAME_LEN,
+	    "%s@s2_%llu", clone1name, (u_longlong_t)id);
+	(void) snprintf(clone2name, ZFS_MAX_DATASET_NAME_LEN,
+	    "%s/c2_%llu", osname, (u_longlong_t)id);
+	(void) snprintf(snap3name, ZFS_MAX_DATASET_NAME_LEN,
+	    "%s@s3_%llu", clone1name, (u_longlong_t)id);
 
 	error = dmu_objset_snapshot_one(osname, strchr(snap1name, '@') + 1);
 	if (error && error != EEXIST) {
@@ -3808,11 +3806,11 @@ out:
 
 	(void) rw_unlock(&ztest_name_lock);
 
-	umem_free(snap1name, MAXNAMELEN);
-	umem_free(clone1name, MAXNAMELEN);
-	umem_free(snap2name, MAXNAMELEN);
-	umem_free(clone2name, MAXNAMELEN);
-	umem_free(snap3name, MAXNAMELEN);
+	umem_free(snap1name, ZFS_MAX_DATASET_NAME_LEN);
+	umem_free(clone1name, ZFS_MAX_DATASET_NAME_LEN);
+	umem_free(snap2name, ZFS_MAX_DATASET_NAME_LEN);
+	umem_free(clone2name, ZFS_MAX_DATASET_NAME_LEN);
+	umem_free(snap3name, ZFS_MAX_DATASET_NAME_LEN);
 }
 
 #undef OD_ARRAY_SIZE
@@ -4622,7 +4620,7 @@ ztest_fzap(ztest_ds_t *zd, uint64_t id)
 	 * 2050 entries we should see ptrtbl growth and leaf-block split.
 	 */
 	for (i = 0; i < 2050; i++) {
-		char name[MAXNAMELEN];
+		char name[ZFS_MAX_DATASET_NAME_LEN];
 		uint64_t value = i;
 		dmu_tx_t *tx;
 		int error;
@@ -5077,7 +5075,7 @@ ztest_dmu_snapshot_hold(ztest_ds_t *zd, uint64_t id)
 	char fullname[100];
 	char clonename[100];
 	char tag[100];
-	char osname[MAXNAMELEN];
+	char osname[ZFS_MAX_DATASET_NAME_LEN];
 	nvlist_t *holds;
 
 	(void) rw_rdlock(&ztest_name_lock);
@@ -5964,13 +5962,13 @@ ztest_thread(void *arg)
 static void
 ztest_dataset_name(char *dsname, char *pool, int d)
 {
-	(void) snprintf(dsname, MAXNAMELEN, "%s/ds_%d", pool, d);
+	(void) snprintf(dsname, ZFS_MAX_DATASET_NAME_LEN, "%s/ds_%d", pool, d);
 }
 
 static void
 ztest_dataset_destroy(int d)
 {
-	char name[MAXNAMELEN];
+	char name[ZFS_MAX_DATASET_NAME_LEN];
 	int t;
 
 	ztest_dataset_name(name, ztest_opts.zo_pool, d);
@@ -6019,7 +6017,7 @@ ztest_dataset_open(int d)
 	uint64_t committed_seq = ZTEST_GET_SHARED_DS(d)->zd_seq;
 	objset_t *os;
 	zilog_t *zilog;
-	char name[MAXNAMELEN];
+	char name[ZFS_MAX_DATASET_NAME_LEN];
 	int error;
 
 	ztest_dataset_name(name, ztest_opts.zo_pool, d);
@@ -6256,8 +6254,8 @@ ztest_run(ztest_shared_t *zs)
 	 * different name.
 	 */
 	if (ztest_random(2) == 0) {
-		char name[MAXNAMELEN];
-		(void) snprintf(name, MAXNAMELEN, "%s_import",
+		char name[ZFS_MAX_DATASET_NAME_LEN];
+		(void) snprintf(name, sizeof (name), "%s_import",
 		    ztest_opts.zo_pool);
 		ztest_spa_import_export(ztest_opts.zo_pool, name);
 		ztest_spa_import_export(name, ztest_opts.zo_pool);
@@ -6834,7 +6832,7 @@ main(int argc, char **argv)
 		if (spa_open(ztest_opts.zo_pool, &spa, FTAG) == 0) {
 			spa_close(spa, FTAG);
 		} else {
-			char tmpname[MAXNAMELEN];
+			char tmpname[ZFS_MAX_DATASET_NAME_LEN];
 			kernel_fini();
 			kernel_init(FREAD | FWRITE);
 			(void) snprintf(tmpname, sizeof (tmpname), "%s_tmp",
diff --git a/cmd/zvol_id/zvol_id_main.c b/cmd/zvol_id/zvol_id_main.c
index 8f0504ae9..6bd5113f1 100644
--- a/cmd/zvol_id/zvol_id_main.c
+++ b/cmd/zvol_id/zvol_id_main.c
@@ -39,14 +39,14 @@ static int
 ioctl_get_msg(char *var, int fd)
 {
 	int error = 0;
-	char msg[ZFS_MAXNAMELEN];
+	char msg[ZFS_MAX_DATASET_NAME_LEN];
 
 	error = ioctl(fd, BLKZNAME, msg);
 	if (error < 0) {
 		return (error);
 	}
 
-	snprintf(var, ZFS_MAXNAMELEN, "%s", msg);
+	snprintf(var, ZFS_MAX_DATASET_NAME_LEN, "%s", msg);
 	return (error);
 }
 
@@ -54,7 +54,8 @@ int
 main(int argc, char **argv)
 {
 	int fd, error = 0;
-	char zvol_name[ZFS_MAXNAMELEN], zvol_name_part[ZFS_MAXNAMELEN];
+	char zvol_name[ZFS_MAX_DATASET_NAME_LEN];
+	char zvol_name_part[ZFS_MAX_DATASET_NAME_LEN];
 	char *dev_name;
 	struct stat64 statbuf;
 	int dev_minor, dev_part;
@@ -87,10 +88,11 @@ main(int argc, char **argv)
 		return (errno);
 	}
 	if (dev_part > 0)
-		snprintf(zvol_name_part, ZFS_MAXNAMELEN, "%s-part%d", zvol_name,
-		    dev_part);
+		snprintf(zvol_name_part, ZFS_MAX_DATASET_NAME_LEN,
+		    "%s-part%d", zvol_name, dev_part);
 	else
-		snprintf(zvol_name_part, ZFS_MAXNAMELEN, "%s", zvol_name);
+		snprintf(zvol_name_part, ZFS_MAX_DATASET_NAME_LEN,
+		    "%s", zvol_name);
 
 	for (i = 0; i < strlen(zvol_name_part); i++) {
 		if (isblank(zvol_name_part[i]))