On 12/7/22 6:01 PM, Michael S. Tsirkin wrote:
On Wed, Dec 07, 2022 at 04:46:31PM +0300, Daniil Tatianin wrote:
The if statement would erroneously check for > ULONG_MAX, which could
never evaluate to true. Check for equality instead.
Found by Linux Verification Center (linuxtesting.org) with the SVACE
static analysis tool.
Signed-off-by: Daniil Tatianin <d-tatianin@xxxxxxxxxxxxxx>
It can trigger on a 32 bit system. I'd also expect more analysis
of the code flow than "this can not trigger switch to a condition
that can" to accompany a patch.
Oops, my bad. It can trigger on 32 bit indeed. Sorry, completely
overlooked that.
Thanks
---
drivers/vhost/vhost.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 40097826cff0..8df706e7bc6c 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -730,7 +730,7 @@ static bool log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
/* Make sure 64 bit math will not overflow. */
static bool vhost_overflow(u64 uaddr, u64 size)
{
- if (uaddr > ULONG_MAX || size > ULONG_MAX)
+ if (uaddr == ULONG_MAX || size == ULONG_MAX)
return true;
if (!size)
--
2.25.1
