GCC: Fixes for gcc 14 on Fedora 40

- Workaround dangling pointer in uu_list.c (#16124)
- Fix calloc() transposed arguments in zpool_vdev_os.c
- Make some temp variables unsigned to prevent triggering a
  '-Werror=alloc-size-larger-than' error.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes #16124
Closes #16125

cmd/zpool/os/linux/zpool_vdev_os.c

@@ -438,7 +438,7 @@ static char *zpool_sysfs_gets(char *path)
 		return (NULL);
 	}
 
-	buf = calloc(sizeof (*buf), statbuf.st_size + 1);
+	buf = calloc(statbuf.st_size + 1, sizeof (*buf));
 	if (buf == NULL) {
 		close(fd);
 		return (NULL);

lib/libuutil/uu_list.c

@@ -505,14 +505,20 @@ uu_list_walk(uu_list_t *lp, uu_walk_fn_t *func, void *private, uint32_t flags)
 	}
 
 	if (lp->ul_debug || robust) {
-		uu_list_walk_t my_walk;
+		uu_list_walk_t *my_walk;
 		void *e;
 
-		list_walk_init(&my_walk, lp, flags);
+		my_walk = uu_zalloc(sizeof (*my_walk));
+		if (my_walk == NULL)
+			return (-1);
+
+		list_walk_init(my_walk, lp, flags);
 		while (status == UU_WALK_NEXT &&
-		    (e = uu_list_walk_next(&my_walk)) != NULL)
+		    (e = uu_list_walk_next(my_walk)) != NULL)
 			status = (*func)(e, private);
-		list_walk_fini(&my_walk);
+		list_walk_fini(my_walk);
+
+		uu_free(my_walk);
 	} else {
 		if (!reverse) {
 			for (np = lp->ul_null_node.uln_next;

module/zfs/vdev_raidz.c

@@ -1283,8 +1283,9 @@ vdev_raidz_matrix_reconstruct(raidz_row_t *rr, int n, int nmissing,
 static void
 vdev_raidz_reconstruct_general(raidz_row_t *rr, int *tgts, int ntgts)
 {
-	int n, i, c, t, tt;
-	int nmissing_rows;
+	int i, c, t, tt;
+	unsigned int n;
+	unsigned int nmissing_rows;
 	int missing_rows[VDEV_RAIDZ_MAXPARITY];
 	int parity_map[VDEV_RAIDZ_MAXPARITY];
 	uint8_t *p, *pp;