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Subject: Re: [PATCH] ath10k: Fix kernel panic due to use after free
From:   Kalle Valo <kvalo@codeaurora.org>
In-Reply-To: <1541753646-11533-1-git-send-email-periyasa@codeaurora.org>
References: <1541753646-11533-1-git-send-email-periyasa@codeaurora.org>
To:     Karthikeyan Periyasamy <periyasa@codeaurora.org>
Cc:     ath10k@lists.infradead.org, linux-wireless@vger.kernel.org,
        Karthikeyan Periyasamy <periyasa@codeaurora.org>
User-Agent: pwcli/0.0.0-git (https://github.com/kvalo/pwcli/) Python/2.7.12
Message-Id: <20181220165139.A410960767@smtp.codeaurora.org>
Date:   Thu, 20 Dec 2018 16:51:39 +0000 (UTC)
Sender: linux-wireless-owner@vger.kernel.org
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Karthikeyan Periyasamy <periyasa@codeaurora.org> wrote:

> This issue arise in a race condition between ath10k_sta_state() and
> ath10k_htt_fetch_peer_stats(), explained in below scenario
> 
> Steps:
> 1. In ath10k_sta_state(), arsta->tx_stats get deallocated before peer deletion
>    when the station moves from IEEE80211_STA_NONE to IEEE80211_STA_NOTEXIST
>    state.
> 2. Meanwhile ath10k receive HTT_T2H_MSG_TYPE_PEER_STATS message.
>    In ath10k_htt_fetch_peer_stats(), arsta->tx_stats get accessed after
>    the peer validation check.
> 
> Since arsta->tx_stats get freed before the peer deletion [1].
> ath10k_htt_fetch_peer_stats() ended up in "use after free" situation.
> 
> Fixed this issue by moving the arsta->tx_stats free handling after the
> peer deletion. so that ath10k_htt_fetch_peer_stats() will not end up in
> "use after free" situation.
> 
> Kernel Panic:
> 
> Unable to handle kernel NULL pointer dereference at virtual address 00000286
> pgd = d8754000
> [00000286] *pgd=00000000
> Internal error: Oops: 5 [#1] PREEMPT SMP ARM
> ...
> CPU: 0 PID: 6245 Comm: hostapd Not tainted
> task: dc44cac0 ti: d4a38000 task.ti: d4a38000
> PC is at kmem_cache_alloc+0x7c/0x114
> LR is at ath10k_sta_state+0x190/0xd58 [ath10k_core]
> pc : [<c02bdc50>]    lr : [<bf916b78>]    psr: 20000013
> sp : d4a39b88  ip : 00000000  fp : 00000001
> r10: 00000000  r9 : 1d3bc000  r8 : 00000dc0
> r7 : 000080d0  r6 : d4a38000  r5 : dd401b00  r4 : 00000286
> r3 : 00000000  r2 : d4a39ba0  r1 : 000080d0  r0 : dd401b00
> Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
> Control: 10c5787d  Table: 5a75406a  DAC: 00000015
> Process hostapd (pid: 6245, stack limit = 0xd4a38238)
> Stack: (0xd4a39b88 to 0xd4a3a000)
> ...
> [<c02bdc50>] (kmem_cache_alloc) from [<bf916b78>] (ath10k_sta_state+0x190/0xd58 [ath10k_core])
> [<bf916b78>] (ath10k_sta_state [ath10k_core]) from [<bf870d4c>] (sta_info_insert_rcu+0x418/0x61c [mac80211])
> [<bf870d4c>] (sta_info_insert_rcu [mac80211]) from [<bf88634c>] (ieee80211_add_station+0xf0/0x134 [mac80211])
> [<bf88634c>] (ieee80211_add_station [mac80211]) from [<bf83f3c4>] (nl80211_new_station+0x330/0x36c [cfg80211])
> [<bf83f3c4>] (nl80211_new_station [cfg80211]) from [<bf6c4040>] (extack_doit+0x2c/0x74 [compat])
> [<bf6c4040>] (extack_doit [compat]) from [<c05c285c>] (genl_rcv_msg+0x274/0x30c)
> [<c05c285c>] (genl_rcv_msg) from [<c05c1d98>] (netlink_rcv_skb+0x58/0xac)
> [<c05c1d98>] (netlink_rcv_skb) from [<c05c25d4>] (genl_rcv+0x20/0x34)
> [<c05c25d4>] (genl_rcv) from [<c05c1750>] (netlink_unicast+0x11c/0x204)
> [<c05c1750>] (netlink_unicast) from [<c05c1be0>] (netlink_sendmsg+0x30c/0x370)
> [<c05c1be0>] (netlink_sendmsg) from [<c0587e90>] (sock_sendmsg+0x70/0x84)
> [<c0587e90>] (sock_sendmsg) from [<c058970c>] (___sys_sendmsg.part.3+0x188/0x228)
> [<c058970c>] (___sys_sendmsg.part.3) from [<c058a594>] (__sys_sendmsg+0x4c/0x70)
> [<c058a594>] (__sys_sendmsg) from [<c0208c80>] (ret_fast_syscall+0x0/0x44)
> Code: ebfffec1 e1a04000 ea00001b e5953014 (e7940003)
> ath10k_pci 0000:01:00.0: SWBA overrun on vdev 0, skipped old beacon
> 
> Hardware tested: QCA9984
> Firmware tested: 10.4-3.6.0.1-00004
> 
> Fixes: a904417fc ("ath10k: add extended per sta tx statistics support")
> Signed-off-by: Karthikeyan Periyasamy <periyasa@codeaurora.org>
> Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

Patch applied to ath-next branch of ath.git, thanks.

553a7cca769d ath10k: fix kernel panic due to use after free

-- 
https://patchwork.kernel.org/patch/10675533/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches