On 08/01/2018 04:50 PM, Eric Blake wrote: > On 08/01/2018 07:16 AM, Daniel P. Berrangé wrote: >> On Wed, Aug 01, 2018 at 01:44:32PM +0200, Michal Privoznik wrote: >>> The function is supposed to return up to 64bit long integer. In >>> order to do that it calls virRandomBytes() to fill the integer >>> with random bytes and then masks out everything but requested >>> bits. However, when doing that it shifts 1U and not 1ULL. So >>> effectively, requesting 32 random bis or more always return 0 >>> which is not random enough. >>> >>> Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx> >>> --- >>> src/util/virrandom.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/src/util/virrandom.c b/src/util/virrandom.c >>> index 01cc82a052..3c011a8615 100644 >>> --- a/src/util/virrandom.c >>> +++ b/src/util/virrandom.c >>> @@ -68,7 +68,7 @@ uint64_t virRandomBits(int nbits) >>> return 0; >>> } >>> - ret &= (1U << nbits) - 1; >>> + ret &= (1ULL << nbits) - 1; > > 1ULL << 64 is undefined in C. We need to write this as: > > if (nbits < 64) > ret &= (1ULL << nbits) - 1; > > Oops. okay. I'll post a patch for that since this is pushed already. Michal -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
