Hello Mike Snitzer,
The patch ae75a25bd83f: "dm crypt: conditionally enable code needed
for tasklet usecases" from Mar 6, 2023, leads to the following Smatch
static checker warning:
drivers/md/dm-crypt.c:2758 crypt_dtr()
warn: 'cc' was already freed.
drivers/md/dm-crypt.c
2739 if (cc->dev)
2740 dm_put_device(ti, cc->dev);
2741
2742 kfree_sensitive(cc->cipher_string);
2743 kfree_sensitive(cc->key_string);
2744 kfree_sensitive(cc->cipher_auth);
2745 kfree_sensitive(cc->authenc_key);
2746
2747 mutex_destroy(&cc->bio_alloc_lock);
2748
2749 /* Must zero key material before freeing */
2750 kfree_sensitive(cc);
^^
2751
2752 spin_lock(&dm_crypt_clients_lock);
2753 WARN_ON(!dm_crypt_clients_n);
2754 dm_crypt_clients_n--;
2755 crypt_calculate_pages_per_client();
2756 spin_unlock(&dm_crypt_clients_lock);
2757
--> 2758 if (test_bit(DM_CRYPT_NO_READ_WORKQUEUE, &cc->flags) ||
^^^^^^^^^
2759 test_bit(DM_CRYPT_NO_WRITE_WORKQUEUE, &cc->flags))
^^^^^^^^^
UAF. This wasn't tested, right? If this passes testing then it means
kfree_sensitive() is broken. (Normally UAF bugs can only be detected
with KASan, but kfree_sensitive() should poison the data I thought).
2760 static_branch_dec(&use_tasklet_enabled);
2761
2762 dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1);
2763 }
regards,
dan carpenter
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