From aaca2aa92785a6ab8e3183e7184bca447a99cd76 Mon Sep 17 00:00:00 2001 From: Zhenzhong Duan Date: Sun, 29 Mar 2026 23:07:55 -0400 Subject: [PATCH] iommufd: Fix return value of iommufd_fault_fops_write() copy_from_user() may return number of bytes failed to copy, we should not pass over this number to user space to cheat that write() succeed. Instead, -EFAULT should be returned. Link: https://patch.msgid.link/r/20260330030755.12856-1-zhenzhong.duan@intel.com Cc: stable@vger.kernel.org Fixes: 07838f7fd529 ("iommufd: Add iommufd fault object") Signed-off-by: Zhenzhong Duan Reviewed-by: Lu Baolu Reviewed-by: Pranjal Shrivastava Reviewed-by: Shuai Xue Reviewed-by: Kevin Tian Signed-off-by: Jason Gunthorpe --- drivers/iommu/iommufd/eventq.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/iommu/iommufd/eventq.c b/drivers/iommu/iommufd/eventq.c index f1e686b3a265..710eef0b6004 100644 --- a/drivers/iommu/iommufd/eventq.c +++ b/drivers/iommu/iommufd/eventq.c @@ -187,9 +187,10 @@ static ssize_t iommufd_fault_fops_write(struct file *filep, const char __user *b mutex_lock(&fault->mutex); while (count > done) { - rc = copy_from_user(&response, buf + done, response_size); - if (rc) + if (copy_from_user(&response, buf + done, response_size)) { + rc = -EFAULT; break; + } static_assert((int)IOMMUFD_PAGE_RESP_SUCCESS == (int)IOMMU_PAGE_RESP_SUCCESS);