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