[Qemu-devel] [PATCH 1/8] qdict: fix unbounded stack for qdict_array_entries

[Peter Xu <peterx@redhat.com>]

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
CC: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 qobject/qdict.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/qobject/qdict.c b/qobject/qdict.c
index 9833bd0..eb602a7 100644
--- a/qobject/qdict.c
+++ b/qobject/qdict.c
@@ -704,17 +704,19 @@ int qdict_array_entries(QDict *src, const char *subqdict)
     for (i = 0; i < INT_MAX; i++) {
         QObject *subqobj;
         int subqdict_entries;
-        size_t slen = 32 + subqdict_len;
-        char indexstr[slen], prefix[slen];
+#define __SLEN_MAX (128)
+        char indexstr[__SLEN_MAX], prefix[__SLEN_MAX];
         size_t snprintf_ret;
 
-        snprintf_ret = snprintf(indexstr, slen, "%s%u", subqdict, i);
-        assert(snprintf_ret < slen);
+        assert(__SLEN_MAX >= 32 + subqdict_len);
+
+        snprintf_ret = snprintf(indexstr, __SLEN_MAX, "%s%u", subqdict, i);
+        assert(snprintf_ret < __SLEN_MAX);
 
         subqobj = qdict_get(src, indexstr);
 
-        snprintf_ret = snprintf(prefix, slen, "%s%u.", subqdict, i);
-        assert(snprintf_ret < slen);
+        snprintf_ret = snprintf(prefix, __SLEN_MAX, "%s%u.", subqdict, i);
+        assert(snprintf_ret < __SLEN_MAX);
 
         subqdict_entries = qdict_count_prefixed_entries(src, prefix);
         if (subqdict_entries < 0) {
@@ -745,6 +747,7 @@ int qdict_array_entries(QDict *src, const char *subqdict)
     }
 
     return i;
+#undef __SLEN_MAX
 }
 
 /**
-- 
2.4.3