Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Arend Van Spriel <arend.vanspriel@broadcom.com>
To:     Kalle Valo <kvalo@kernel.org>,
        Minsuk Kang <linuxlovemin@yonsei.ac.kr>
CC:     <linux-wireless@vger.kernel.org>, <dokyungs@yonsei.ac.kr>,
        <jisoo.jang@yonsei.ac.kr>, Minsuk Kang <linuxlovemin@yonsei.ac.kr>,
        kernel test robot <lkp@intel.com>
Date:   Thu, 22 Dec 2022 17:14:06 +0100
Message-ID: <1853a9d00b0.279b.9b12b7fc0a3841636cfb5e919b41b954@broadcom.com>
In-Reply-To: <167172452509.8231.8186319479061770376.kvalo@kernel.org>
References: <20221116145821.544266-1-linuxlovemin@yonsei.ac.kr>
 <167172452509.8231.8186319479061770376.kvalo@kernel.org>
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Subject: Re: [PATCH v2] wifi: brcmfmac: Fix potential slab-out-of-bounds read in brcmf_inform_single_bss()
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On December 22, 2022 4:55:31 PM Kalle Valo <kvalo@kernel.org> wrote:

> Minsuk Kang <linuxlovemin@yonsei.ac.kr> wrote:
>
>> This patch fixes a slab-out-of-bounds read in brcmfmac that occurs in
>> cfg80211_find_elem_match() called from brcmf_inform_single_bss() when
>> the offset and length values of information elements provided by the
>> device exceed the boundary of the escan buffer that contains information
>> elements. The patch adds a check that makes the function return -EINVAL
>> if that is the case. Note that the negative return is handled by the
>> caller, brcmf_inform_bss().
>>
>> Found by a modified version of syzkaller.
>>
>> ==================================================================
>> BUG: KASAN: slab-out-of-bounds in cfg80211_find_elem_match+0x164/0x180
>> Read of size 1 at addr ffff888018f0fde9 by task kworker/0:2/1896
>>
>> CPU: 0 PID: 1896 Comm: kworker/0:2 Tainted: G           O      5.14.0+ #139
>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 
>> rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
>> Workqueue: events brcmf_fweh_event_worker
>> Call Trace:
>> dump_stack_lvl+0x8e/0xd1
>> print_address_description.constprop.0.cold+0x93/0x334
>> ? cfg80211_find_elem_match+0x164/0x180
>> kasan_report.cold+0x79/0xd5
>> ? cfg80211_find_elem_match+0x164/0x180
>> cfg80211_find_elem_match+0x164/0x180
>> cfg80211_get_bss_channel+0x69/0x320
>> cfg80211_inform_single_bss_data+0x1a6/0x1060
>> ? cfg80211_bss_update+0x1e20/0x1e20
>> ? rcu_read_lock_sched_held+0xa1/0xd0
>> ? rcu_read_lock_bh_held+0xb0/0xb0
>> ? find_held_lock+0x2d/0x110
>> ? cfg80211_inform_bss_data+0xcb/0x160
>> cfg80211_inform_bss_data+0xcb/0x160
>> ? cfg80211_parse_mbssid_data+0x1540/0x1540
>> ? kvm_clock_get_cycles+0x14/0x20
>> ? ktime_get_with_offset+0x2b9/0x450
>> brcmf_inform_single_bss+0x36d/0x4d0
>> ? brcmf_notify_mic_status+0xb0/0xb0
>> ? __lock_acquire+0x181f/0x5790
>> ? brcmf_p2p_cancel_remain_on_channel+0x30/0x30
>> brcmf_inform_bss+0x131/0x210
>> brcmf_cfg80211_escan_handler+0x779/0xd20
>> ? rcu_read_lock_bh_held+0xb0/0xb0
>> ? lock_acquire+0x19d/0x4e0
>> ? find_held_lock+0x2d/0x110
>> ? brcmf_cfg80211_escan_timeout_worker+0x60/0x60
>> ? brcmf_fweh_event_worker+0x249/0xc00
>> ? mark_held_locks+0x9f/0xe0
>> ? lockdep_hardirqs_on_prepare+0x3e0/0x3e0
>> ? brcmf_cfg80211_escan_timeout_worker+0x60/0x60
>> brcmf_fweh_call_event_handler.isra.0+0x90/0x100
>> brcmf_fweh_event_worker+0x117/0xc00
>> ? brcmf_fweh_call_event_handler.isra.0+0x100/0x100
>> ? rcu_read_lock_sched_held+0xa1/0xd0
>> ? rcu_read_lock_bh_held+0xb0/0xb0
>> ? lockdep_hardirqs_on_prepare+0x273/0x3e0
>> process_one_work+0x92b/0x1460
>> ? pwq_dec_nr_in_flight+0x330/0x330
>> ? rwlock_bug.part.0+0x90/0x90
>> worker_thread+0x95/0xe00
>> ? __kthread_parkme+0x115/0x1e0
>> ? process_one_work+0x1460/0x1460
>> kthread+0x3a1/0x480
>> ? set_kthread_struct+0x120/0x120
>> ret_from_fork+0x1f/0x30
>>
>> The buggy address belongs to the page:
>> page:ffffea000063c000 refcount:1 mapcount:0 mapping:0000000000000000 
>> index:0x0 pfn:0x18f00
>> head:ffffea000063c000 order:4 compound_mapcount:0 compound_pincount:0
>> flags: 0x100000000010000(head|node=0|zone=1)
>> raw: 0100000000010000 0000000000000000 dead000000000122 0000000000000000
>> raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
>> page dumped because: kasan: bad access detected
>> page_owner tracks the page as allocated
>> page last allocated via order 4, migratetype Unmovable, gfp_mask 
>> 0x40dc0(GFP_KERNEL|__GFP_COMP|__GFP_ZERO), pid 1896, ts 44510886600, free_ts 0
>> prep_new_page+0x1aa/0x240
>> get_page_from_freelist+0x159a/0x27c0
>> __alloc_pages+0x2da/0x6a0
>> alloc_pages+0xec/0x1e0
>> kmalloc_order+0x39/0xf0
>> kmalloc_order_trace+0x19/0x120
>> brcmf_cfg80211_attach+0x5c9/0x3fd0
>> brcmf_attach+0x389/0xd40
>> brcmf_usb_probe+0x12de/0x1690
>> usb_probe_interface+0x2aa/0x760
>> really_probe+0x205/0xb70
>> __driver_probe_device+0x311/0x4b0
>> driver_probe_device+0x4e/0x150
>> __device_attach_driver+0x1cc/0x2a0
>> bus_for_each_drv+0x156/0x1d0
>> __device_attach+0x23f/0x3a0
>> page_owner free stack trace missing
>>
>> Memory state around the buggy address:
>> ffff888018f0fc80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>> ffff888018f0fd00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>> ffff888018f0fd80: 00 00 00 00 00 00 00 00 00 00 00 00 00 fe fe fe
>>                                                  ^
>> ffff888018f0fe00: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
>> ffff888018f0fe80: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe
>> ==================================================================
>>
>> Reported-by: Dokyung Song <dokyungs@yonsei.ac.kr>
>> Reported-by: Jisoo Jang <jisoo.jang@yonsei.ac.kr>
>> Reported-by: Minsuk Kang <linuxlovemin@yonsei.ac.kr>
>> Reported-by: kernel test robot <lkp@intel.com>
>> Signed-off-by: Minsuk Kang <linuxlovemin@yonsei.ac.kr>
>
> Can someone review this?

Will have to see the bigger picture. Probably have time to do that later 
today. What's the deadline? ;-)

Regards,
Arend

> --
> https://patchwork.kernel.org/project/linux-wireless/patch/20221116145821.544266-1-linuxlovemin@yonsei.ac.kr/
>
> https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches


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