Re: [PATCH 2/2] vhost: Fix the calculation in vhost_overflow()

This fixes the incorrect calculation for integer overflow
when the last address of iova range is 0xffffffff.

Fixes: ec33d031a14b ("vhost: detect 32 bit integer wrap around“)
Reported-by: Jason Wang <redacted>
Signed-off-by: Xie Yongji <redacted>
---
  drivers/vhost/vhost.c | 3 ++-
  1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index b9e853e6094d..a9fd1b311d2f 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c

@@ -738,7 +738,8 @@ static bool log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
  static bool vhost_overflow(u64 uaddr, u64 size)
  {
  	/* Make sure 64 bit math will not overflow. */
-	return uaddr > ULONG_MAX || size > ULONG_MAX || uaddr > ULONG_MAX - size;
+	return uaddr > ULONG_MAX || size > ULONG_MAX ||
+	       uaddr - 1 > ULONG_MAX - size;
  }