From 26e33b1984cce3549df170f58f8221201ad54cfd Mon Sep 17 00:00:00 2001 From: Alexey Tikhonov Date: Tue, 7 Jan 2020 16:29:05 +0100 Subject: [PATCH] util/sss_ptr_hash: fixed double free in sss_ptr_hash_delete_cb() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Calling data->callback(value->ptr) in sss_ptr_hash_delete_cb() could lead to freeing of value->ptr and thus to destruction of value->spy that is attached to value->ptr. In turn sss_ptr_hash_spy_destructor() calls sss_ptr_hash_delete() -> hash_delete() -> sss_ptr_hash_delete_cb() again and in this recursive execution hash entry was actually deleted and value was freed. When stack was unwound back to "first" sss_ptr_hash_delete_cb() it tried to free value again => double free. To prevent this bug value and hence spy are now freed before execution of data->callback(value->ptr). Resolves: https://pagure.io/SSSD/sssd/issue/4135 Reviewed-by: Pavel Březina --- src/util/sss_ptr_hash.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/src/util/sss_ptr_hash.c b/src/util/sss_ptr_hash.c index c7403ffa6..8f9762cb9 100644 --- a/src/util/sss_ptr_hash.c +++ b/src/util/sss_ptr_hash.c @@ -154,13 +154,13 @@ sss_ptr_hash_delete_cb(hash_entry_t *item, callback_entry.value.type = HASH_VALUE_PTR; callback_entry.value.ptr = value->ptr; + /* Free value, this also will disable spy */ + talloc_free(value); + /* Switch to the input value and call custom callback. */ if (data->callback != NULL) { data->callback(&callback_entry, deltype, data->pvt); } - - /* Free value. */ - talloc_free(value); } hash_table_t *sss_ptr_hash_create(TALLOC_CTX *mem_ctx, -- 2.20.1