linux-kernel - [PATCH v2 4/6] module: sysfs: Simplify section attribute allocation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20241227-sysfs-const-bin_attr-module-v2-4-e267275f0f37@weissschuh.net>
Date: Fri, 27 Dec 2024 14:23:23 +0100
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Luis Chamberlain <mcgrof@...nel.org>, Petr Pavlu <petr.pavlu@...e.com>, 
 Sami Tolvanen <samitolvanen@...gle.com>, 
 Daniel Gomez <da.gomez@...sung.com>, Kees Cook <kees@...nel.org>, 
 "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc: linux-modules@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-hardening@...r.kernel.org, 
 Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH v2 4/6] 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 <linux@...ssschuh.net>
---
 kernel/module/sysfs.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/kernel/module/sysfs.c b/kernel/module/sysfs.c
index 3d507005d7111b8328c04d35476a73193f73db1c..4b1a963b712b609cde1c4375e789a6ee7f359c7a 100644
--- a/kernel/module/sysfs.c
+++ b/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)

-- 
2.47.1