From: Mark Langsdorf <mlangsdo@redhat.com> mainline inclusion from mainline-v5.13-rc1 commit 1cfd8956437f842836e8a066b40d1ec2fc01f13e category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5LBE7 CVE: NA -------------------------------- 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@redhat.com> Cc: 5.4+ <stable@vger.kernel.org> # 5.4+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com> Reviewed-by: Hanjun Guo <guohanjun@huawei.com> Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com> --- 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 222ea3f12f41..1ed6d24ae1c9 100644 --- a/drivers/acpi/custom_method.c +++ b/drivers/acpi/custom_method.c @@ -37,6 +37,8 @@ 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; -- 2.25.1