diff --git a/cmd/zpool/zpool_iter.c b/cmd/zpool/zpool_iter.c
index d70d266699cf..3d7a0cfc35e6 100644
--- a/cmd/zpool/zpool_iter.c
+++ b/cmd/zpool/zpool_iter.c
@@ -494,19 +494,25 @@ vdev_run_cmd(vdev_cmd_data_t *data, char *cmd)
 	/* Setup our custom environment variables */
 	rc = asprintf(&env[1], "VDEV_PATH=%s",
 	    data->path ? data->path : "");
-	if (rc == -1)
+	if (rc == -1) {
+		env[1] = NULL;
 		goto out;
+	}
 
 	rc = asprintf(&env[2], "VDEV_UPATH=%s",
 	    data->upath ? data->upath : "");
-	if (rc == -1)
+	if (rc == -1) {
+		env[2] = NULL;
 		goto out;
+	}
 
 	rc = asprintf(&env[3], "VDEV_ENC_SYSFS_PATH=%s",
 	    data->vdev_enc_sysfs_path ?
 	    data->vdev_enc_sysfs_path : "");
-	if (rc == -1)
+	if (rc == -1) {
+		env[3] = NULL;
 		goto out;
+	}
 
 	/* Run the command */
 	rc = libzfs_run_process_get_stdout_nopath(cmd, argv, env, &lines,
@@ -525,8 +531,7 @@ vdev_run_cmd(vdev_cmd_data_t *data, char *cmd)
 
 	/* Start with i = 1 since env[0] was statically allocated */
 	for (i = 1; i < ARRAY_SIZE(env); i++)
-		if (env[i] != NULL)
-			free(env[i]);
+		free(env[i]);
 }
 
 /*
diff --git a/lib/libzfs/libzfs_pool.c b/lib/libzfs/libzfs_pool.c
index b4c9d7df90b6..d4849ee5bd9b 100644
--- a/lib/libzfs/libzfs_pool.c
+++ b/lib/libzfs/libzfs_pool.c
@@ -4812,14 +4812,14 @@ zpool_load_compat(const char *compat, boolean_t *features, char *report,
 	    file != NULL;
 	    file = strtok_r(NULL, ",", &ps)) {
 
-		boolean_t l_features[SPA_FEATURES];
+		boolean_t l_features[SPA_FEATURES] = {B_FALSE};
 
 		enum { Z_SYSCONF, Z_DATA } source;
 
 		/* try sysconfdir first, then datadir */
 		source = Z_SYSCONF;
-		if ((featfd = openat(sdirfd, file, 0, O_RDONLY)) < 0) {
-			featfd = openat(ddirfd, file, 0, O_RDONLY);
+		if ((featfd = openat(sdirfd, file, O_RDONLY | O_CLOEXEC)) < 0) {
+			featfd = openat(ddirfd, file, O_RDONLY | O_CLOEXEC);
 			source = Z_DATA;
 		}
 
@@ -4835,13 +4835,18 @@ zpool_load_compat(const char *compat, boolean_t *features, char *report,
 			continue;
 		}
 
+#if !defined(MAP_POPULATE) && defined(MAP_PREFAULT_READ)
+#define	MAP_POPULATE MAP_PREFAULT_READ
+#elif !defined(MAP_POPULATE)
+#define	MAP_POPULATE 0
+#endif
 		/* private mmap() so we can strtok safely */
 		fc = (char *)mmap(NULL, fs.st_size,
-		    PROT_READ|PROT_WRITE, MAP_PRIVATE, featfd, 0);
+		    PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_POPULATE, featfd, 0);
 		(void) close(featfd);
 
 		/* map ok, and last character == newline? */
-		if (fc < 0 || fc[fs.st_size - 1] != '\n') {
+		if (fc == MAP_FAILED || fc[fs.st_size - 1] != '\n') {
 			(void) munmap((void *) fc, fs.st_size);
 			strlcat(err_badfile, file, ZFS_MAXPROPLEN);
 			strlcat(err_badfile, " ", ZFS_MAXPROPLEN);
@@ -4851,9 +4856,6 @@ zpool_load_compat(const char *compat, boolean_t *features, char *report,
 
 		ret_nofiles = B_FALSE;
 
-		for (uint_t i = 0; i < SPA_FEATURES; i++)
-			l_features[i] = B_FALSE;
-
 		/* replace last char with NUL to ensure we have a delimiter */
 		fc[fs.st_size - 1] = '\0';
 
diff --git a/lib/libzfs/libzfs_util.c b/lib/libzfs/libzfs_util.c
index 8038f7fa343e..7840e3590a57 100644
--- a/lib/libzfs/libzfs_util.c
+++ b/lib/libzfs/libzfs_util.c
@@ -782,8 +782,10 @@ zfs_asprintf(libzfs_handle_t *hdl, const char *fmt, ...)
 
 	va_end(ap);
 
-	if (err < 0)
+	if (err < 0) {
 		(void) no_memory(hdl);
+		ret = NULL;
+	}
 
 	return (ret);
 }
diff --git a/lib/libzfsbootenv/lzbe_device.c b/lib/libzfsbootenv/lzbe_device.c
index b366bd9c7f57..2d8833b4fff2 100644
--- a/lib/libzfsbootenv/lzbe_device.c
+++ b/lib/libzfsbootenv/lzbe_device.c
@@ -88,12 +88,11 @@ lzbe_set_boot_device(const char *pool, lzbe_flags_t flag, const char *device)
 		if (strncmp(device, "zfs:", 4) == 0) {
 			fnvlist_add_string(nv, OS_BOOTONCE, device);
 		} else {
-			descriptor = NULL;
-			if (asprintf(&descriptor, "zfs:%s:", device) > 0)
+			if (asprintf(&descriptor, "zfs:%s:", device) > 0) {
 				fnvlist_add_string(nv, OS_BOOTONCE, descriptor);
-			else
+				free(descriptor);
+			} else
 				rv = ENOMEM;
-			free(descriptor);
 		}
 	}
 
diff --git a/lib/libzutil/os/linux/zutil_device_path_os.c b/lib/libzutil/os/linux/zutil_device_path_os.c
index da7ffba764a8..2a6f4ae2a222 100644
--- a/lib/libzutil/os/linux/zutil_device_path_os.c
+++ b/lib/libzutil/os/linux/zutil_device_path_os.c
@@ -195,10 +195,8 @@ zfs_get_enclosure_sysfs_path(const char *dev_name)
 	}
 
 	dp = opendir(tmp1);
-	if (dp == NULL) {
-		tmp1 = NULL;	/* To make free() at the end a NOP */
+	if (dp == NULL)
 		goto end;
-	}
 
 	/*
 	 * Look though all sysfs entries in /sys/block/<dev>/device for
@@ -209,18 +207,16 @@ zfs_get_enclosure_sysfs_path(const char *dev_name)
 		if (strstr(ep->d_name, "enclosure_device") == NULL)
 			continue;
 
-		if (asprintf(&tmp2, "%s/%s", tmp1, ep->d_name) == -1 ||
-		    tmp2 == NULL)
+		if (asprintf(&tmp2, "%s/%s", tmp1, ep->d_name) == -1) {
+			tmp2 = NULL;
 			break;
+		}
 
 		size = readlink(tmp2, buf, sizeof (buf));
 
 		/* Did readlink fail or crop the link name? */
-		if (size == -1 || size >= sizeof (buf)) {
-			free(tmp2);
-			tmp2 = NULL;	/* To make free() at the end a NOP */
+		if (size == -1 || size >= sizeof (buf))
 			break;
-		}
 
 		/*
 		 * We got a valid link.  readlink() doesn't terminate strings
@@ -306,9 +302,10 @@ dm_get_underlying_path(const char *dm_name)
 	else
 		dev_str = tmp;
 
-	size = asprintf(&tmp, "/sys/block/%s/slaves/", dev_str);
-	if (size == -1 || !tmp)
+	if ((size = asprintf(&tmp, "/sys/block/%s/slaves/", dev_str)) == -1) {
+		tmp = NULL;
 		goto end;
+	}
 
 	dp = opendir(tmp);
 	if (dp == NULL)
@@ -334,7 +331,9 @@ dm_get_underlying_path(const char *dm_name)
 			if (!enclosure_path)
 				continue;
 
-			size = asprintf(&path, "/dev/%s", ep->d_name);
+			if ((size = asprintf(
+			    &path, "/dev/%s", ep->d_name)) == -1)
+				path = NULL;
 			free(enclosure_path);
 			break;
 		}
@@ -352,7 +351,8 @@ dm_get_underlying_path(const char *dm_name)
 		 * enclosure devices.  Throw up out hands and return the first
 		 * underlying path.
 		 */
-		size = asprintf(&path, "/dev/%s", first_path);
+		if ((size = asprintf(&path, "/dev/%s", first_path)) == -1)
+			path = NULL;
 	}
 
 	free(first_path);