[Qemu-devel] [PATCH v2] qdict: fix unbounded stack warning for qdict_array_entries

[Qemu-devel] [PATCH v2] qdict: fix unbounded stack warning for qdict_array_entries

[Peter Xu]

Here we use one g_strdup_printf() to replace the two stack allocated
array, considering it's more convenient, safe, and as long as it's
called rarely only when quorum device opens. This will remove the
unbound stack warning when compiling with "-Wstack-usage=1000000".

Reviewed-by:   Eric Blake <eblake@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 qobject/qdict.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/qobject/qdict.c b/qobject/qdict.c
index 9833bd0..fe6ffa1 100644
--- a/qobject/qdict.c
+++ b/qobject/qdict.c
@@ -704,19 +704,16 @@ 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];
-        size_t snprintf_ret;
+        char *prefix = g_strdup_printf("%s%u.", subqdict, i);
 
-        snprintf_ret = snprintf(indexstr, slen, "%s%u", subqdict, i);
-        assert(snprintf_ret < slen);
+        subqdict_entries = qdict_count_prefixed_entries(src, prefix);
 
-        subqobj = qdict_get(src, indexstr);
+        /* Remove ending "." */
+        prefix[strlen(prefix) - 1] = 0;
+        subqobj = qdict_get(src, prefix);
 
-        snprintf_ret = snprintf(prefix, slen, "%s%u.", subqdict, i);
-        assert(snprintf_ret < slen);
+        g_free(prefix);
 
-        subqdict_entries = qdict_count_prefixed_entries(src, prefix);
         if (subqdict_entries < 0) {
             return subqdict_entries;
         }
-- 
2.4.3

Re: [Qemu-devel] [PATCH v2] qdict: fix unbounded stack warning for qdict_array_entries

[Markus Armbruster]

Peter Xu <peterx@redhat.com> writes:

> Here we use one g_strdup_printf() to replace the two stack allocated
> array, considering it's more convenient, safe, and as long as it's
> called rarely only when quorum device opens. This will remove the
> unbound stack warning when compiling with "-Wstack-usage=1000000".
>
> Reviewed-by:   Eric Blake <eblake@redhat.com>
> Signed-off-by: Peter Xu <peterx@redhat.com>

Reviewed-by: Markus Armbruster <armbru@redhat.com>

I lack the time to take this through my tree before my Easter vacation.
Nominating for qemu-trivial, assuming Luiz doesn't mind.

Re: [Qemu-devel] [PATCH v2] qdict: fix unbounded stack warning for qdict_array_entries

[Michael Tokarev]

22.03.2016 18:39, Markus Armbruster wrote:
> Peter Xu <peterx@redhat.com> writes:
> 
>> Here we use one g_strdup_printf() to replace the two stack allocated
>> array, considering it's more convenient, safe, and as long as it's
>> called rarely only when quorum device opens. This will remove the
>> unbound stack warning when compiling with "-Wstack-usage=1000000".
>>
>> Reviewed-by:   Eric Blake <eblake@redhat.com>
>> Signed-off-by: Peter Xu <peterx@redhat.com>
> 
> Reviewed-by: Markus Armbruster <armbru@redhat.com>
> 
> I lack the time to take this through my tree before my Easter vacation.
> Nominating for qemu-trivial, assuming Luiz doesn't mind.

(Finally) applied to -trivial, thanks!

/mjt