[Qemu-block] [PATCH 2/2] iov: assert that qiov->size doesn't exceed INT_MAX

[Alberto Garcia]

The type of qiov->size is size_t but the QEMU I/O code uses int all
over the place to measure request sizes. Overflows are likely going
to be detected by any of the many assert(qiov->size == nbytes), where
nbytes is an int, but let's add proper checks in the QEMUIOVector
initialization, which is where it belongs.

Signed-off-by: Alberto Garcia <address@hidden>
---
 util/iov.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/util/iov.c b/util/iov.c
index 74e6ca8ed7..6b5cc9203c 100644
--- a/util/iov.c
+++ b/util/iov.c
@@ -283,13 +283,18 @@ void qemu_iovec_init_external(QEMUIOVector *qiov, struct 
iovec *iov, int niov)
     qiov->niov = niov;
     qiov->nalloc = -1;
     qiov->size = 0;
-    for (i = 0; i < niov; i++)
+    for (i = 0; i < niov; i++) {
+        assert(iov[i].iov_len <= INT_MAX);
+        assert(qiov->size <= INT_MAX - iov[i].iov_len);
         qiov->size += iov[i].iov_len;
+    }
 }
 
 void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len)
 {
     assert(qiov->nalloc != -1);
+    assert(len <= INT_MAX);
+    assert(qiov->size <= INT_MAX - len);
 
     if (qiov->niov == qiov->nalloc) {
         qiov->nalloc = 2 * qiov->nalloc + 1;
-- 
2.11.0