From: Xie Yongji Date: Wed, 28 Jul 2021 13:07:56 +0000 (+0800) Subject: vhost: Fix the calculation in vhost_overflow() X-Git-Tag: v4.19.205~22 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=7cfaec657d4124e4a3d8372849de416da784515d;p=users%2Fdwmw2%2Flinux.git 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 Signed-off-by: Xie Yongji Acked-by: Jason Wang Link: https://lore.kernel.org/r/20210728130756.97-2-xieyongji@bytedance.com Signed-off-by: Michael S. Tsirkin Signed-off-by: Sasha Levin --- diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 732327756ee11..7a58f629155d2 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -678,10 +678,16 @@ 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. */