[PULL,06/13] util/iov: Avoid dynamic stack allocation

Commit Message

Eric Blake Sept. 8, 2023, 1:35 a.m. UTC

From: Philippe Mathieu-Daudé <[e-mail]>

Use autofree heap allocation instead of variable-length array on the
stack.

The codebase has very few VLAs, and if we can get rid of them all we
can make the compiler error on new additions.  This is a defensive
measure against security bugs where an on-stack dynamic allocation
isn't correctly size-checked (e.g.  CVE-2021-3527).

Signed-off-by: Philippe Mathieu-Daudé <[e-mail]>
Signed-off-by: Peter Maydell <[e-mail]>
Message-ID: <[e-mail]>
Reviewed-by: Eric Blake <[e-mail]>
Signed-off-by: Eric Blake <[e-mail]>
---
 util/iov.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

diff --git a/util/iov.c b/util/iov.c
index 866fb577f30..7e73948f5e3 100644
--- a/util/iov.c
+++ b/util/iov.c
@@ -571,7 +571,7 @@  static int sortelem_cmp_src_index(const void *a, const void *b)
  */
 void qemu_iovec_clone(QEMUIOVector *dest, const QEMUIOVector *src, void *buf)
 {
-    IOVectorSortElem sortelems[src->niov];
+    g_autofree IOVectorSortElem *sortelems = g_new(IOVectorSortElem, src->niov);
     void *last_end;
     int i;