Implement ->proc_write_buf() so procfs copies in what is written before
it pins the entry, and take the multiplier from that copy. Writes
larger than PAGE_SIZE - 1 bytes fail with -EINVAL now.
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
---
kernel/profile.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/kernel/profile.c b/kernel/profile.c
index e7defa90a34c..6e4b34f35e3b 100644
--- a/kernel/profile.c
+++ b/kernel/profile.c
@@ -189,16 +189,14 @@ int __weak setup_profiling_timer(unsigned mult)
* Writing a 'profiling multiplier' value into it also re-sets the profiling
* interrupt frequency, on architectures that support this.
*/
-static ssize_t write_profile(struct file *file, const char __user *buf,
- size_t count, loff_t *ppos)
+static ssize_t write_profile(struct file *file, char *buf, size_t count,
+ loff_t *ppos)
{
#ifdef CONFIG_SMP
if (count == sizeof(int)) {
unsigned int multiplier;
- if (copy_from_user(&multiplier, buf, sizeof(int)))
- return -EFAULT;
-
+ memcpy(&multiplier, buf, sizeof(int));
if (setup_profiling_timer(multiplier))
return -EINVAL;
}@@ -209,7 +207,7 @@ static ssize_t write_profile(struct file *file, const char __user *buf,
static const struct proc_ops profile_proc_ops = {
.proc_read = read_profile,
- .proc_write = write_profile,
+ .proc_write_buf = write_profile,
.proc_lseek = default_llseek,
};
--
2.53.0