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Date: Tue, 27 Feb 2024 01:05:30 +0300
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>
Subject: Re: [PATCH] crypto: sun8i-ce - Fix use after free in unprepare.
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	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>,
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	Arnaud Ferraris <arnaud.ferraris@collabora.com>
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On 24-02-27 00:53, Andrey Skvortsov wrote:
> 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.

And potentially rk3288_crypto driver is affected by the similar
problem.

https://elixir.bootlin.com/linux/v6.8-rc6/source/drivers/crypto/rockchip/rk3288_crypto_ahash.c#L339

> 
> 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")

-- 
Best regards,
Andrey Skvortsov