module: sysfs: Simplify section attribute allocation

The existing allocation logic manually stuffs two allocations into one.
This is hard to understand and of limited value, given that all the
section names are allocated on their own anyways.
Une one allocation per datastructure.

Signed-off-by: Thomas Weißschuh <[email protected]>
Reviewed-by: Petr Pavlu <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Link: https://lore.kernel.org/r/20241227-sysfs-const-bin_attr-module-v2-4-e267275f0f37@weissschuh.net
Signed-off-by: Petr Pavlu <[email protected]>

Author: t-8ch

kernel/module/sysfs.c

@@ -58,34 +58,37 @@ static void free_sect_attrs(struct module_sect_attrs *sect_attrs)
 
 	for (bin_attr = sect_attrs->grp.bin_attrs; *bin_attr; bin_attr++)
 		kfree((*bin_attr)->attr.name);
+	kfree(sect_attrs->grp.bin_attrs);
 	kfree(sect_attrs);
 }
 
 static int add_sect_attrs(struct module *mod, const struct load_info *info)
 {
-	unsigned int nloaded = 0, i, size[2];
 	struct module_sect_attrs *sect_attrs;
 	struct bin_attribute **gattr;
 	struct bin_attribute *sattr;
+	unsigned int nloaded = 0, i;
 	int ret;
 
 	/* Count loaded sections and allocate structures */
 	for (i = 0; i < info->hdr->e_shnum; i++)
 		if (!sect_empty(&info->sechdrs[i]))
 			nloaded++;
-	size[0] = ALIGN(struct_size(sect_attrs, attrs, nloaded),
-			sizeof(sect_attrs->grp.bin_attrs[0]));
-	size[1] = (nloaded + 1) * sizeof(sect_attrs->grp.bin_attrs[0]);
-	sect_attrs = kzalloc(size[0] + size[1], GFP_KERNEL);
+	sect_attrs = kzalloc(struct_size(sect_attrs, attrs, nloaded), GFP_KERNEL);
 	if (!sect_attrs)
 		return -ENOMEM;
 
+	gattr = kcalloc(nloaded + 1, sizeof(*gattr), GFP_KERNEL);
+	if (!gattr) {
+		kfree(sect_attrs);
+		return -ENOMEM;
+	}
+
 	/* Setup section attributes. */
 	sect_attrs->grp.name = "sections";
-	sect_attrs->grp.bin_attrs = (void *)sect_attrs + size[0];
+	sect_attrs->grp.bin_attrs = gattr;
 
 	sattr = &sect_attrs->attrs[0];
-	gattr = &sect_attrs->grp.bin_attrs[0];
 	for (i = 0; i < info->hdr->e_shnum; i++) {
 		Elf_Shdr *sec = &info->sechdrs[i];
 
@@ -104,7 +107,6 @@ static int add_sect_attrs(struct module *mod, const struct load_info *info)
 		sattr->attr.mode = 0400;
 		*(gattr++) = sattr++;
 	}
-	*gattr = NULL;
 
 	ret = sysfs_create_group(&mod->mkobj.kobj, &sect_attrs->grp);
 	if (ret)