In cm_write(), if the 'buf' is allocated memory but not fully consumed,
it is possible to reallocate the buffer without freeing it by passing
'*ppos' as 0 on a subsequent call.
Add an explicit kfree() before kzalloc() to prevent the possible memory
leak.
Fixes: 526b4af47f44 ("ACPI: Split out custom_method functionality into an own driver")
Signed-off-by: Mark Langsdorf <mlangsdo@xxxxxxxxxx>
---
drivers/acpi/custom_method.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c
index 443fdf62dd22..6dc96f2cef1d 100644
--- a/drivers/acpi/custom_method.c
+++ b/drivers/acpi/custom_method.c
@@ -42,6 +42,8 @@ static ssize_t cm_write(struct file *file, const char __user *user_buf,
sizeof(struct acpi_table_header)))
return -EFAULT;
uncopied_bytes = max_size = table.length;
+ /* make sure the buf is not allocated */
+ kfree(buf);
buf = kzalloc(max_size, GFP_KERNEL);
if (!buf)
return -ENOMEM;
--
2.26.3
