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Message-ID: <bea1f663-0dfd-e1c4-29c5-1f6251a24c31@gmail.com>
Date:   Tue, 12 Jul 2022 10:08:39 +0200
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Subject: Re: [PATCH v5] brcmfmac: prevent double-free on hardware-reset
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To:     Danny van Heumen <danny@dannyvanheumen.nl>,
        "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Cc:     Franky Lin <franky.lin@broadcom.com>,
        Hante Meuleman <hante.meuleman@broadcom.com>,
        Ulf Hansson <ulf.hansson@linaro.org>
References: <id1HN6qCMAirApBzTA6fT7ZFWBBGCJhULpflxQ7NT6cgCboVnn3RHpiOFjA9SbRqzBRFLk9ES0C4FNvO6fUQsNg7pqF6ZSNAYUo99nHy8PY=@dannyvanheumen.nl>
From:   Arend Van Spriel <aspriel@gmail.com>
In-Reply-To: <id1HN6qCMAirApBzTA6fT7ZFWBBGCJhULpflxQ7NT6cgCboVnn3RHpiOFjA9SbRqzBRFLk9ES0C4FNvO6fUQsNg7pqF6ZSNAYUo99nHy8PY=@dannyvanheumen.nl>
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On 7/12/2022 1:21 AM, Danny van Heumen wrote:
> In case of buggy firmware, brcmfmac may perform a hardware reset. If during
> reset and subsequent probing an early failure occurs, a memory region is
> accidentally double-freed. With hardened memory allocation enabled, this error
> will be detected.
> 
> - return early where appropriate to skip unnecessary clean-up.
> - set '.freezer' pointer to NULL to prevent double-freeing under possible
>    other circumstances and to re-align result under various different
>    behaviors of memory allocation freeing.
> - correctly claim host on func1 for disabling func2.
> - after reset, do not initiate probing immediately, but rely on events.
> 
> Given a firmware crash, function 'brcmf_sdio_bus_reset' is called. It calls
> 'brcmf_sdiod_remove', then follows up with 'brcmf_sdiod_probe' to reinitialize
> the hardware. If 'brcmf_sdiod_probe' fails to "set F1 blocksize", it exits
> early, which includes calling 'brcmf_sdiod_remove'. In both cases
> 'brcmf_sdiod_freezer_detach' is called to free allocated '.freezer', which
> has not yet been re-allocated the second time.
> 
> Stacktrace of (failing) hardware reset after firmware-crash:
> 
> Code: b9402b82 8b0202c0 eb1a02df 54000041 (d4210000)
>   ret_from_fork+0x10/0x20
>   kthread+0x154/0x160
>   worker_thread+0x188/0x504
>   process_one_work+0x1f4/0x490
>   brcmf_core_bus_reset+0x34/0x44 [brcmfmac]
>   brcmf_sdio_bus_reset+0x68/0xc0 [brcmfmac]
>   brcmf_sdiod_probe+0x170/0x21c [brcmfmac]
>   brcmf_sdiod_remove+0x48/0xc0 [brcmfmac]
>   kfree+0x210/0x220
>   __slab_free+0x58/0x40c
> Call trace:
> x2 : 0000000000000040 x1 : fffffc00002d2b80 x0 : ffff00000b4aee40
> x5 : ffff8000013fa728 x4 : 0000000000000001 x3 : ffff00000b4aee00
> x8 : ffff800009967ce0 x7 : ffff8000099bfce0 x6 : 00000006f8005d01
> x11: ffff8000099bfce0 x10: 00000000fffff000 x9 : ffff8000083401d0
> x14: 0000000000000000 x13: 657a69736b636f6c x12: 6220314620746573
> x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000030
> x20: fffffc00002d2ba0 x19: fffffc00002d2b80 x18: 0000000000000000
> x23: ffff00000b4aee00 x22: ffff00000b4aee00 x21: 0000000000000001
> x26: ffff00000b4aee00 x25: ffff0000f7753705 x24: 000000000001288a
> x29: ffff80000a22bbf0 x28: ffff000000401200 x27: 000000008020001a
> sp : ffff80000a22bbf0
> lr : kfree+0x210/0x220
> pc : __slab_free+0x58/0x40c
> pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> Workqueue: events brcmf_core_bus_reset [brcmfmac]
> Hardware name: Pine64 Pinebook Pro (DT)
> CPU: 2 PID: 639 Comm: kworker/2:2 Tainted: G         C        5.16.0-0.bpo.4-arm64 #1  Debian 5.16.12-1~bpo11+1
>   nvmem_rockchip_efuse industrialio_triggered_buffer videodev snd_soc_core snd_pcm_dmaengine kfifo_buf snd_pcm io_domain mc industrialio mt>
> Modules linked in: snd_seq_dummy snd_hrtimer snd_seq snd_seq_device nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reje>
> Internal error: Oops - BUG: 0 [#1] SMP
> kernel BUG at mm/slub.c:379!

Reviewed-by: Arend van Spriel <aspriel.gmail.com>
> Signed-off-by: Danny van Heumen <danny@dannyvanheumen.nl>
> ---
>   .../wireless/broadcom/brcm80211/brcmfmac/bcmsdh.c   | 13 +++++--------
>   .../net/wireless/broadcom/brcm80211/brcmfmac/sdio.c | 10 +---------
>   2 files changed, 6 insertions(+), 17 deletions(-)