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Re: [syslog-ng] [PATCH 4/7] [affile]: Fix a possible double free
From: Gergely Nagy <algernon_at_nospam>Date: Sat May 28 2011 - 12:33:49 GMT
To: Syslog-ng users' and developers' mailing list <syslog-ng@lists.balabit.hu>
>> From: Juhasz Viktor <jviktor@balabit.hu>
>>
>> Duplicate the filename we insert into self->writer_hash, because
>> otherwise, we're likely to end up trying to free it twice.
>>
>> Signed-off-by: Viktor Juhasz <jviktor@balabit.hu>
>> ---
>> modules/affile/affile.c | 2 +-
>> 1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/modules/affile/affile.c b/modules/affile/affile.c
>> index c5e89f5..f6c70e9 100644
>> --- a/modules/affile/affile.c
>> +++ b/modules/affile/affile.c
>> @@ -1046,7 +1046,7 @@ affile_dd_open_writer(gpointer args[])
>> {
>> log_pipe_ref(&next->super);
>> g_static_mutex_lock(&self->lock);
>> - g_hash_table_insert(self->writer_hash, filename->str, next);
>> + g_hash_table_insert(self->writer_hash, strdup(filename->str), next);
>> g_static_mutex_unlock(&self->lock);
>> }
>> }
>
> I don't understand. The writer_hash hashtable contains a borrowed key,
> nothing frees it there. Isn't it possible that the last patch (which
> changed AFFileDestWriter->filename allocation) fixed this issue too?
That's very possible, indeed. After having a closer look, I believe that
the other patch fixed this issue aswell.
> And even if the strdup was necessary, g_strdup() should have been used,
> as the g_malloc() style allocations may not map directly to malloc() on
> some platforms.
Yikes, my bad! I didn't spot it's not g_strdup().
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