Implement ->proc_write_buf() so procfs copies in what is written before
it pins the entry, and parse the command from that copy. Writes larger
than PAGE_SIZE - 1 bytes fail with -EINVAL now.
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
---
arch/x86/kernel/cpu/mtrr/if.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/cpu/mtrr/if.c b/arch/x86/kernel/cpu/mtrr/if.c
index 9510e01d5103..038e2dc38797 100644
--- a/arch/x86/kernel/cpu/mtrr/if.c
+++ b/arch/x86/kernel/cpu/mtrr/if.c
@@ -91,7 +91,7 @@ mtrr_file_del(unsigned long base, unsigned long size,
* "base=%Lx size=%Lx type=%s" or "disable=%d"
*/
static ssize_t
-mtrr_write(struct file *file, const char __user *buf, size_t len, loff_t * ppos)
+mtrr_write(struct file *file, char *buf, size_t len, loff_t * ppos)
{
int i, err;
unsigned long reg;@@ -103,9 +103,8 @@ mtrr_write(struct file *file, const char __user *buf, size_t len, loff_t * ppos)
memset(line, 0, LINE_SIZE);
len = min_t(size_t, len, LINE_SIZE - 1);
- length = strncpy_from_user(line, buf, len);
- if (length < 0)
- return length;
+ length = strnlen(buf, len);
+ memcpy(line, buf, length);
ptr = line + length - 1;
if (length && *ptr == '\n')
@@ -397,7 +396,7 @@ static int mtrr_open(struct inode *inode, struct file *file)
static const struct proc_ops mtrr_proc_ops = {
.proc_show = mtrr_seq_show,
.proc_open = mtrr_open,
- .proc_write = mtrr_write,
+ .proc_write_buf = mtrr_write,
.proc_ioctl = mtrr_ioctl,
#ifdef CONFIG_COMPAT
.proc_compat_ioctl = mtrr_ioctl,
--
2.53.0