[PATCH] crypto: sun8i-ce - Fix use after free in unprepare.

From: Andrey Skvortsov <andrej.skvortzov@gmail.com>
To: Corentin Labbe <clabbe.montjoie@gmail.com>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>,
	Chen-Yu Tsai <wens@csie.org>,
	Jernej Skrabec <jernej.skrabec@gmail.com>,
	Samuel Holland <samuel@sholland.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Ovidiu Panait <ovidiu.panait@windriver.com>,
	linux-crypto@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-sunxi@lists.linux.dev, linux-kernel@vger.kernel.org
Cc: Arnaud Ferraris <arnaud.ferraris@collabora.com>,
	Andrey Skvortsov <andrej.skvortzov@gmail.com>
Subject: [PATCH] crypto: sun8i-ce - Fix use after free in unprepare.
Date: Tue, 27 Feb 2024 00:53:57 +0300	[thread overview]
Message-ID: <20240226215358.555234-1-andrej.skvortzov@gmail.com> (raw)

sun8i_ce_cipher_unprepare should be called before
crypto_finalize_skcipher_request, because client callbacks may
immediately free memory, that isn't needed anymore. But it will be
used by unprepare after free. Before removing prepare/unprepare
callbacks it was handled by crypto engine in crypto_finalize_request.

Usually that results in a pointer dereference problem during a in
crypto selftest.
 Unable to handle kernel NULL pointer dereference at
                                      virtual address 0000000000000030
 Mem abort info:
   ESR = 0x0000000096000004
   EC = 0x25: DABT (current EL), IL = 32 bits
   SET = 0, FnV = 0
   EA = 0, S1PTW = 0
   FSC = 0x04: level 0 translation fault
 Data abort info:
   ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
 user pgtable: 4k pages, 48-bit VAs, pgdp=000000004716d000
 [0000000000000030] pgd=0000000000000000, p4d=0000000000000000
 Internal error: Oops: 0000000096000004 [#1] SMP

This problem is detected by KASAN as well.
 ==================================================================
 BUG: KASAN: slab-use-after-free in sun8i_ce_cipher_do_one+0x6e8/0xf80 [sun8i_ce]
 Read of size 8 at addr ffff00000dcdc040 by task 1c15000.crypto-/373

 Hardware name: Pine64 PinePhone (1.2) (DT)
 Call trace:
  dump_backtrace+0x9c/0x128
  show_stack+0x20/0x38
  dump_stack_lvl+0x48/0x60
  print_report+0xf8/0x5d8
  kasan_report+0x90/0xd0
  __asan_load8+0x9c/0xc0
  sun8i_ce_cipher_do_one+0x6e8/0xf80 [sun8i_ce]
  crypto_pump_work+0x354/0x620 [crypto_engine]
  kthread_worker_fn+0x244/0x498
  kthread+0x168/0x178
  ret_from_fork+0x10/0x20

 Allocated by task 379:
  kasan_save_stack+0x3c/0x68
  kasan_set_track+0x2c/0x40
  kasan_save_alloc_info+0x24/0x38
  __kasan_kmalloc+0xd4/0xd8
  __kmalloc+0x74/0x1d0
  alg_test_skcipher+0x90/0x1f0
  alg_test+0x24c/0x830
  cryptomgr_test+0x38/0x60
  kthread+0x168/0x178
  ret_from_fork+0x10/0x20

 Freed by task 379:
  kasan_save_stack+0x3c/0x68
  kasan_set_track+0x2c/0x40
  kasan_save_free_info+0x38/0x60
  __kasan_slab_free+0x100/0x170
  slab_free_freelist_hook+0xd4/0x1e8
  __kmem_cache_free+0x15c/0x290
  kfree+0x74/0x100
  kfree_sensitive+0x80/0xb0
  alg_test_skcipher+0x12c/0x1f0
  alg_test+0x24c/0x830
  cryptomgr_test+0x38/0x60
  kthread+0x168/0x178
  ret_from_fork+0x10/0x20

 The buggy address belongs to the object at ffff00000dcdc000
  which belongs to the cache kmalloc-256 of size 256
 The buggy address is located 64 bytes inside of
  freed 256-byte region [ffff00000dcdc000, ffff00000dcdc100)

Signed-off-by: Andrey Skvortsov <andrej.skvortzov@gmail.com>
Fixes: 4136212ab18e ("crypto: sun8i-ce - Remove prepare/unprepare request")
---
 .../allwinner/sun8i-ce/sun8i-ce-cipher.c      | 34 +++++++++----------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c b/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c
index 1262a7773ef3..de50c00ba218 100644
--- a/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c
+++ b/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c
@@ -299,22 +299,6 @@ static int sun8i_ce_cipher_prepare(struct crypto_engine *engine, void *async_req
 	return err;
 }
 
-static void sun8i_ce_cipher_run(struct crypto_engine *engine, void *areq)
-{
-	struct skcipher_request *breq = container_of(areq, struct skcipher_request, base);
-	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(breq);
-	struct sun8i_cipher_tfm_ctx *op = crypto_skcipher_ctx(tfm);
-	struct sun8i_ce_dev *ce = op->ce;
-	struct sun8i_cipher_req_ctx *rctx = skcipher_request_ctx(breq);
-	int flow, err;
-
-	flow = rctx->flow;
-	err = sun8i_ce_run_task(ce, flow, crypto_tfm_alg_name(breq->base.tfm));
-	local_bh_disable();
-	crypto_finalize_skcipher_request(engine, breq, err);
-	local_bh_enable();
-}
-
 static void sun8i_ce_cipher_unprepare(struct crypto_engine *engine,
 				      void *async_req)
 {
@@ -360,6 +344,23 @@ static void sun8i_ce_cipher_unprepare(struct crypto_engine *engine,
 	dma_unmap_single(ce->dev, rctx->addr_key, op->keylen, DMA_TO_DEVICE);
 }
 
+static void sun8i_ce_cipher_run(struct crypto_engine *engine, void *areq)
+{
+	struct skcipher_request *breq = container_of(areq, struct skcipher_request, base);
+	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(breq);
+	struct sun8i_cipher_tfm_ctx *op = crypto_skcipher_ctx(tfm);
+	struct sun8i_ce_dev *ce = op->ce;
+	struct sun8i_cipher_req_ctx *rctx = skcipher_request_ctx(breq);
+	int flow, err;
+
+	flow = rctx->flow;
+	err = sun8i_ce_run_task(ce, flow, crypto_tfm_alg_name(breq->base.tfm));
+	sun8i_ce_cipher_unprepare(engine, areq);
+	local_bh_disable();
+	crypto_finalize_skcipher_request(engine, breq, err);
+	local_bh_enable();
+}
+
 int sun8i_ce_cipher_do_one(struct crypto_engine *engine, void *areq)
 {
 	int err = sun8i_ce_cipher_prepare(engine, areq);
@@ -368,7 +369,6 @@ int sun8i_ce_cipher_do_one(struct crypto_engine *engine, void *areq)
 		return err;
 
 	sun8i_ce_cipher_run(engine, areq);
-	sun8i_ce_cipher_unprepare(engine, areq);
 	return 0;
 }
 
-- 
2.43.0

