| Message ID | 20221207134631.907221-1-d-tatianin@yandex-team.ru (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v1] drivers/vhost/vhost: fix overflow checks in vhost_overflow | expand |
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@yandex-team.ru> 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. > --- > 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
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@yandex-team.ru> > > 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 >
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)
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@yandex-team.ru> --- drivers/vhost/vhost.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)