From: Xie Yongji xieyongji@bytedance.com
[ Upstream commit f7ad318ea0ad58ebe0e595e59aed270bb643b29b ]
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 jasowang@redhat.com Signed-off-by: Xie Yongji xieyongji@bytedance.com Acked-by: Jason Wang jasowang@redhat.com Link: https://lore.kernel.org/r/20210728130756.97-2-xieyongji@bytedance.com Signed-off-by: Michael S. Tsirkin mst@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/vhost/vhost.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 4b5590f4e98b..93cdeb516594 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -685,10 +685,16 @@ static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz) (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8); }
+/* Make sure 64 bit math will not overflow. */ 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; + if (uaddr > ULONG_MAX || size > ULONG_MAX) + return true; + + if (!size) + return false; + + return uaddr > ULONG_MAX - size + 1; }
/* Caller should have vq mutex and device mutex. */