The ALLOCA(3) man-page mentions its "use is discouraged".

Use autofree heap allocation instead (returning ENOMEM on failure).

Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 bsd-user/syscall.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/bsd-user/syscall.c b/bsd-user/syscall.c
index 4abff796c76..6db05988f1b 100644
--- a/bsd-user/syscall.c
+++ b/bsd-user/syscall.c
@@ -355,9 +355,12 @@ abi_long do_freebsd_syscall(void *cpu_env, int num, abi_long arg1,
     case TARGET_FREEBSD_NR_writev:
         {
             int count = arg3;
-            struct iovec *vec;
+            g_autofree struct iovec *vec = g_try_new(struct iovec, count);
 
-            vec = alloca(count * sizeof(struct iovec));
+            if (!vec) {
+                ret = -TARGET_ENOMEM;
+                goto fail;
+            }
             if (lock_iovec(VERIFY_READ, vec, arg2, count, 1) < 0)
                 goto efault;
             ret = get_errno(writev(arg1, vec, count));
-- 
2.26.3