[SSSD] [PATCH] pac: fix double free
Pavel Březina
pbrezina at redhat.com
Fri Nov 15 12:45:15 UTC 2013
On 11/13/2013 11:43 AM, Sumit Bose wrote:
> On Tue, Nov 12, 2013 at 01:42:32PM +0100, Pavel Březina wrote:
>> On 11/12/2013 10:03 AM, Sumit Bose wrote:
>>> On Mon, Nov 11, 2013 at 12:50:54PM +0100, Pavel Březina wrote:
>>>
>>>> From f9f6e1ce452f9dc507c4779e6ff74aea412e9457 Mon Sep 17 00:00:00 2001
>>>> From: =?UTF-8?q?Pavel=20B=C5=99ezina?= <pbrezina at redhat.com>
>>>> Date: Mon, 11 Nov 2013 12:47:53 +0100
>>>> Subject: [PATCH] pac: fix double free
>>>>
>>>> ---
>>>> src/responder/pac/pacsrv_utils.c | 14 ++++++--------
>>>> 1 file changed, 6 insertions(+), 8 deletions(-)
>>>>
>>>> diff --git a/src/responder/pac/pacsrv_utils.c b/src/responder/pac/pacsrv_utils.c
>>>> index 30055a1345b7d943e6adf822438263c92e53b51a..8380247b10c74d8acabec8e1a8c22944aab38320 100644
>>>> --- a/src/responder/pac/pacsrv_utils.c
>>>> +++ b/src/responder/pac/pacsrv_utils.c
>>>> @@ -74,6 +74,7 @@ errno_t get_sids_from_pac(TALLOC_CTX *mem_ctx,
>>>> struct sss_domain_info *user_dom;
>>>> struct sss_domain_info *group_dom;
>>>> char *sid_str = NULL;
>>>> + char *msid_str = NULL;
>>>> char *user_dom_sid_str = NULL;
>>>> size_t user_dom_sid_str_len;
>>>> enum idmap_error_code err;
>>>> @@ -231,24 +232,22 @@ errno_t get_sids_from_pac(TALLOC_CTX *mem_ctx,
>>>>
>>>> }
>>>>
>>>> - talloc_zfree(sid_str);
>>>> -
>>>> for(s = 0; s < info3->sidcount; s++) {
>>>> err = sss_idmap_smb_sid_to_sid(pac_ctx->idmap_ctx, info3->sids[s].sid,
>>>> - &sid_str);
>>>> + &msid_str);
>>>> if (err != IDMAP_SUCCESS) {
>>>> DEBUG(SSSDBG_OP_FAILURE, ("sss_idmap_smb_sid_to_sid failed.\n"));
>>>> ret = EFAULT;
>>>> goto done;
>>>> }
>>>>
>>>> - key.str = sid_str;
>>>> + key.str = msid_str;
>>>> value.ul = 0;
>>>>
>>>> - ret = responder_get_domain_by_id(pac_ctx->rctx, sid_str, &group_dom);
>>>> + ret = responder_get_domain_by_id(pac_ctx->rctx, msid_str, &group_dom);
>>>> if (ret == EOK) {
>>>> ret = sysdb_search_object_by_sid(mem_ctx, group_dom->sysdb,
>>>> - group_dom, sid_str, NULL, &msg);
>>>> + group_dom, msid_str, NULL, &msg);
>>>> if (ret == EOK && msg->count == 1 ) {
>>>> value.ul = ldb_msg_find_attr_as_uint64(msg->msgs[0],
>>>> SYSDB_GIDNUM, 0);
>>>> @@ -263,14 +262,13 @@ errno_t get_sids_from_pac(TALLOC_CTX *mem_ctx,
>>>> ret = EIO;
>>>> goto done;
>>>> }
>>>> -
>>>> - sss_idmap_free_sid(pac_ctx->idmap_ctx, sid_str);
>>>
>>> I think this should be replaced by
>>>
>>> sss_idmap_free_sid(pac_ctx->idmap_ctx, msid_str);
>>> msid_str = NULL;
>>>
>>> otherwise only the last allocated msid_str will be freed in the done
>>> section.
>
> There is no change in first patch related to this ^^^ comment.
Sorry, I overlooked it. It turned out that it is even more tricky, since
msid_str is inserted into a hash table that is returned via output
parameter so it should not be freed at all.
I stealed it on sid_table instead of freeing it now.
>
> bye,
> Sumit
>
>>>
>>>> }
>>>>
>>>> ret = EOK;
>>>>
>>>> done:
>>>> talloc_free(sid_str);
>>>> + sss_idmap_free_sid(pac_ctx->idmap_ctx, msid_str);
>>>> sss_idmap_free_sid(pac_ctx->idmap_ctx, user_dom_sid_str);
>>>>
>>>> if (ret == EOK) {
>>>> --
>>>> 1.7.11.7
>>>>
>>>
>>> While looking at the code I think there is a potential memory leak in
>>> this section as well:
>>>
>>> ret = responder_get_domain_by_id(pac_ctx->rctx, sid_str, &group_dom);
>>> if (ret == EOK) {
>>> ret = sysdb_search_object_by_sid(mem_ctx, group_dom->sysdb,
>>> group_dom, sid_str, NULL, &msg);
>>> if (ret == EOK && msg->count == 1 ) {
>>> value.ul = ldb_msg_find_attr_as_uint64(msg->msgs[0],
>>> SYSDB_GIDNUM, 0);
>>> talloc_free(msg);
>>> }
>>> }
>>>
>>> while msg should not be set if ret != EOK it will certainly be set if
>>> msg->count != 1. Although it should never happen would you mind to
>>> remove the talloc_free(msg) out of the if block and add a
>>> talloc_zfree(msg) after the if block?
>>
>> Nice catch. Patches are attached.
>>
>>
>>
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