RDMA/ucma: Fix uABI structure layouts for 32/64 compat
The rdma_ucm_event_resp is a different length on 32 and 64 bit compiles.
The kernel requires it to be the expected length or longer so 32 bit
builds running on a 64 bit kernel will not work.
Retain full compat by having all kernels accept a struct with or without
the trailing reserved field.
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index 4bb5bed..db4190b 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -382,7 +382,11 @@ static ssize_t ucma_get_event(struct ucma_file *file, const char __user *inbuf,
struct ucma_event *uevent;
int ret = 0;
- if (out_len < sizeof uevent->resp)
+ /*
+ * Old 32 bit user space does not send the 4 byte padding in the
+ * reserved field. We don't care, allow it to keep working.
+ */
+ if (out_len < sizeof(uevent->resp) - sizeof(uevent->resp.reserved))
return -ENOSPC;
if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
@@ -417,7 +421,8 @@ static ssize_t ucma_get_event(struct ucma_file *file, const char __user *inbuf,
}
if (copy_to_user((void __user *)(unsigned long)cmd.response,
- &uevent->resp, sizeof uevent->resp)) {
+ &uevent->resp,
+ min_t(size_t, out_len, sizeof(uevent->resp)))) {
ret = -EFAULT;
goto done;
}