memfd: Avoid Coverity warning about integer overflow

Coverity complains about qemu_memfd_create() (CID 1385858) because
we calculate a bit position htsize which could be up to 63, but
then use it in "1 << htsize" which is a 32-bit integer calculation
and could push the 1 off the top of the value.

Silence the complaint bu using "1ULL"; this isn't a bug in
practice since a hugetlbsize of 4GB is not very plausible.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20180515172729.24564-1-peter.maydell@linaro.org>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/util/memfd.c b/util/memfd.c
index b3ecbac19e9017e0aa4868da7837e7ec305a96e3..d248a53c3c0815bee3a5b2e2309ddcff51c10b2a 100644 (file)
--- a/util/memfd.c
+++ b/util/memfd.c
@@ -66,7 +66,7 @@ int qemu_memfd_create(const char *name, size_t size, bool hugetlb,
 {
     int htsize = hugetlbsize ? ctz64(hugetlbsize) : 0;
 
-    if (htsize && 1 << htsize != hugetlbsize) {
+    if (htsize && 1ULL << htsize != hugetlbsize) {
         error_setg(errp, "Hugepage size must be a power of 2");
         return -1;
     }