[PATCH] proc: use kmalloc instead of __get_free_page() to alloc path buffer

Hao Lee
2022-01-23T10:08:45Z

It's not a standard approach that use __get_free_page() to alloc path
buffer directly. We'd better use kmalloc and PATH_MAX.

Signed-off-by: Hao Lee <haolee.swjtu@gmail.com>
---
fs/proc/base.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index d654ce7150fd..74cfef87fe45 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1764,25 +1764,26 @@ static const char *proc_pid_get_link(struct dentry *dentry,

static int do_proc_readlink(struct path *path, char __user *buffer, int buflen)
{
- char *tmp = (char *)__get_free_page(GFP_KERNEL);
+ char *buf = NULL;
char *pathname;
int len;

- if (!tmp)
+ buf = kmalloc(PATH_MAX, GFP_KERNEL);
+ if (!buf)
return -ENOMEM;

- pathname = d_path(path, tmp, PAGE_SIZE);
+ pathname = d_path(path, buf, PATH_MAX);
len = PTR_ERR(pathname);
if (IS_ERR(pathname))
goto out;
- len = tmp + PAGE_SIZE - 1 - pathname;
+ len = buf + PATH_MAX - 1 - pathname;

if (len > buflen)
len = buflen;
if (copy_to_user(buffer, pathname, len))
len = -EFAULT;
out:
- free_page((unsigned long)tmp);
+ kfree(buf);
return len;
}

--
2.34.1