This is a note to let you know that I've just added the patch titled
vhost: Fix the calculation in vhost_overflow()
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
vhost-fix-the-calculation-in-vhost_overflow.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit bcb9042bb3f5a18e6885131afb7ddbbffa90a04f
Author: Xie Yongji <xieyongji@xxxxxxxxxxxxx>
Date: Wed Jul 28 21:07:56 2021 +0800
vhost: Fix the calculation in vhost_overflow()
[ 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@xxxxxxxxxx>
Signed-off-by: Xie Yongji <xieyongji@xxxxxxxxxxxxx>
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210728130756.97-2-xieyongji@xxxxxxxxxxxxx
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index a279ecacbf60..97be299f0a8d 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -702,10 +702,16 @@ static bool 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. */
