[PATCH 1/3] selinux: use k[mz]alloc() to allocate temporary buffers

[Mike Rapoport (Microsoft)]

Several functions in selinuxfs.c allocate temporary buffers using
__get_free_page() or get_zeroed_page().

These buffers are used either to store a string generated by snprintf() (in
sel_make_bools()) or to copy data from user (sel_read_avc_hash_stats() and
sel_read_sidtab_hash_stats()).

Such usage does not require struct page access and it is better to allocate
these buffers with kzalloc()/kmalloc() that provide better scalability and
more debugging possibilities.

Replace use of get_zeroed_page() with kzalloc() and usage of
__get_free_page() with kmalloc().

Link: https://lore.kernel.org/all/635405e4-9423-4a25-a6e7-e03c8ea0bcbe@redhat.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt at kernel.org>
---
 security/selinux/selinuxfs.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index 25ca7d714014..e7b884eedf80 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -1244,7 +1244,7 @@ static int sel_make_bools(struct selinux_policy *newpolicy, struct dentry *bool_
 	char **names, *page;
 	u32 i, num;
 
-	page = (char *)get_zeroed_page(GFP_KERNEL);
+	page = kzalloc(PAGE_SIZE, GFP_KERNEL);
 	if (!page)
 		return -ENOMEM;
 
@@ -1290,7 +1290,7 @@ static int sel_make_bools(struct selinux_policy *newpolicy, struct dentry *bool_
 		ret = sel_attach_file(bool_dir, names[i], inode);
 	}
 out:
-	free_page((unsigned long)page);
+	kfree(page);
 	return ret;
 }
 
@@ -1349,14 +1349,14 @@ static ssize_t sel_read_avc_hash_stats(struct file *filp, char __user *buf,
 	char *page;
 	ssize_t length;
 
-	page = (char *)__get_free_page(GFP_KERNEL);
+	page = kmalloc(PAGE_SIZE, GFP_KERNEL);
 	if (!page)
 		return -ENOMEM;
 
 	length = avc_get_hash_stats(page);
 	if (length >= 0)
 		length = simple_read_from_buffer(buf, count, ppos, page, length);
-	free_page((unsigned long)page);
+	kfree(page);
 
 	return length;
 }
@@ -1367,7 +1367,7 @@ static ssize_t sel_read_sidtab_hash_stats(struct file *filp, char __user *buf,
 	char *page;
 	ssize_t length;
 
-	page = (char *)__get_free_page(GFP_KERNEL);
+	page = kmalloc(PAGE_SIZE, GFP_KERNEL);
 	if (!page)
 		return -ENOMEM;
 
@@ -1375,7 +1375,7 @@ static ssize_t sel_read_sidtab_hash_stats(struct file *filp, char __user *buf,
 	if (length >= 0)
 		length = simple_read_from_buffer(buf, count, ppos, page,
 						length);
-	free_page((unsigned long)page);
+	kfree(page);
 
 	return length;
 }

-- 
2.53.0