From e873c74132f0c5f1452816cd9bb26208f0bba1e1 Mon Sep 17 00:00:00 2001 From: Shivank Garg Date: Sat, 22 Aug 2026 19:22:05 +0000 Subject: dmaengine: fix use-after-free in dma_chan_put() and dma_release_channel() When dma_device_put() drops the last reference on chan->device->ref, dma_device_release() runs and may free the dma_device along with its channels. dma_chan_put() then still reads chan->device->owner via dma_chan_to_owner() for the trailing module_put(). KASAN catches it: slab-use-after-free in dma_chan_put+0x3e6/0x4c0 Read of size 8 by task insmod/6319 Freed by task 6319: kfree+0x225/0x470 dma_chan_put+0x395/0x4c0 dmaengine_put+0xf8/0x160 Cache the module owner in dma_chan_put() before the put so the trailing module_put() does not need chan->device. Fixes: 8ad342a86359 ("dmaengine: Add reference counting to dma_device struct") Suggested-by: Sashiko Link: https://sashiko.dev/#/patchset/20260518-dmaengine-kref-fix-v1-1-4d6125048fb7@amd.com Reviewed-by: Frank Li Reviewed-by: Logan Gunthorpe Signed-off-by: Shivank Garg Link: https://patch.msgid.link/20260822-dmaengine-kref-fix-v5-3-d4a4ee47d927@amd.com Signed-off-by: Vinod Koul --- crypto/crypto_null.c | 124 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 124 insertions(+) create mode 100644 crypto/crypto_null.c (limited to 'crypto/crypto_null.c') diff --git a/crypto/crypto_null.c b/crypto/crypto_null.c new file mode 100644 index 000000000..fea151df1 --- /dev/null +++ b/crypto/crypto_null.c @@ -0,0 +1,124 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Cryptographic API. + * + * Null algorithms, aka Much Ado About Nothing. + * + * These are needed for IPsec, and may be useful in general for + * testing & debugging. + * + * The null cipher is compliant with RFC2410. + * + * Copyright (c) 2002 James Morris + */ + +#include +#include +#include +#include +#include +#include +#include + +static int null_init(struct shash_desc *desc) +{ + return 0; +} + +static int null_update(struct shash_desc *desc, const u8 *data, + unsigned int len) +{ + return 0; +} + +static int null_final(struct shash_desc *desc, u8 *out) +{ + return 0; +} + +static int null_digest(struct shash_desc *desc, const u8 *data, + unsigned int len, u8 *out) +{ + return 0; +} + +static int null_hash_setkey(struct crypto_shash *tfm, const u8 *key, + unsigned int keylen) +{ return 0; } + +static int null_skcipher_setkey(struct crypto_skcipher *tfm, const u8 *key, + unsigned int keylen) +{ return 0; } + +static int null_skcipher_crypt(struct skcipher_request *req) +{ + if (req->src != req->dst) + memcpy_sglist(req->dst, req->src, req->cryptlen); + return 0; +} + +static struct shash_alg digest_null = { + .digestsize = NULL_DIGEST_SIZE, + .setkey = null_hash_setkey, + .init = null_init, + .update = null_update, + .finup = null_digest, + .digest = null_digest, + .final = null_final, + .base = { + .cra_name = "digest_null", + .cra_driver_name = "digest_null-generic", + .cra_blocksize = NULL_BLOCK_SIZE, + .cra_module = THIS_MODULE, + } +}; + +static struct skcipher_alg skcipher_null = { + .base.cra_name = "ecb(cipher_null)", + .base.cra_driver_name = "ecb-cipher_null", + .base.cra_priority = 100, + .base.cra_blocksize = NULL_BLOCK_SIZE, + .base.cra_ctxsize = 0, + .base.cra_module = THIS_MODULE, + .min_keysize = NULL_KEY_SIZE, + .max_keysize = NULL_KEY_SIZE, + .ivsize = NULL_IV_SIZE, + .setkey = null_skcipher_setkey, + .encrypt = null_skcipher_crypt, + .decrypt = null_skcipher_crypt, +}; + +MODULE_ALIAS_CRYPTO("digest_null"); +MODULE_ALIAS_CRYPTO("ecb(cipher_null)"); + +static int __init crypto_null_mod_init(void) +{ + int ret = 0; + + ret = crypto_register_shash(&digest_null); + if (ret < 0) + goto out; + + ret = crypto_register_skcipher(&skcipher_null); + if (ret < 0) + goto out_unregister_shash; + + return 0; + +out_unregister_shash: + crypto_unregister_shash(&digest_null); +out: + return ret; +} + +static void __exit crypto_null_mod_fini(void) +{ + crypto_unregister_shash(&digest_null); + crypto_unregister_skcipher(&skcipher_null); +} + +module_init(crypto_null_mod_init); +module_exit(crypto_null_mod_fini); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Null Cryptographic Algorithms"); -- cgit v1.3.1