[PATCH for-next 13/13] IB/hfi1: Split copy_to_user data copy for better security

Dennis Dalessandro
2017-07-24T14:46:42Z

From: Michael J. Ruhl <michael.j.ruhl-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>

A copy_to_user() call assumes that two members of a data structure
are sequential. Since this may not always be true, separate the copies
to ensure a safe copy.

Reviewed-by: Dennis Dalessandro <dennis.dalessandro-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: Michael J. Ruhl <michael.j.ruhl-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
drivers/infiniband/hw/hfi1/file_ops.c | 8 +++++---
1 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/file_ops.c b/drivers/infiniband/hw/hfi1/file_ops.c
index 7be75e0..650c1e5 100644
--- a/drivers/infiniband/hw/hfi1/file_ops.c
+++ b/drivers/infiniband/hw/hfi1/file_ops.c
@@ -268,12 +268,14 @@ static long hfi1_file_ioctl(struct file *fp, unsigned int cmd,
/*
* Copy the number of tidlist entries we used
* and the length of the buffer we registered.
- * These fields are adjacent in the structure so
- * we can copy them at the same time.
*/
addr = arg + offsetof(struct hfi1_tid_info, tidcnt);
if (copy_to_user((void __user *)addr, &tinfo.tidcnt,
- sizeof(tinfo.tidcnt) +
+ sizeof(tinfo.tidcnt)))
+ return -EFAULT;
+
+ addr = arg + offsetof(struct hfi1_tid_info, length);
+ if (copy_to_user((void __user *)addr, &tinfo.length,
sizeof(tinfo.length)))
ret = -EFAULT;