[PATCH v2] ath10k: reset pointer after memory free to avoid kernel crash by multi-free

[Wen Gong]

Please ignore this patch.

On 4/8/2022 3:23 PM, Wen Gong wrote:
> When WMI command timed out happened in ath10k_wmi_cmd_send(), recovery
> started, then ath10k_core_restart()->ath10k_halt()->ath10k_core_stop()->
> ath10k_htt_rx_free() called for the 1st time, then ath10k_core_restart()->
> ieee80211_restart_hw()->queue_work() called, then ieee80211_restart_work()
> is queued in worker at the moment. Then suspend operation arrived and
> wiphy_suspend called and it acquired rtnl_lock, and then called into
> ath10k_stop()->ath10k_halt()->ath10k_core_stop()->ath10k_htt_rx_free(),
> meanwhile ieee80211_restart_work() is waiting the rtnl_lock, so
> ath10k_htt_rx_alloc() can not be called by ieee80211_restart_work()->
> ieee80211_reconfig()->drv_start()->ath10k_start()->ath10k_core_start(),
> then the memory freed for the 2nd time in ath10k_htt_rx_free() at this
> moment, and kernel crash happened as below call stack.
>
> Rest pointer to NULL for free memory to avoid multi-free.
>
> [  428.469167] ------------[ cut here ]------------
> [  428.469180] kernel BUG at mm/slub.c:4150!
> [  428.469193] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
> [  428.469203] CPU: 1 PID: 147 Comm: kworker/u4:4 Tainted: G        W         5.10.91-14222-ga1c4b1c83299 #1 620a72c7194de0370fd0a984a6f7032a6ed43d6c
> [  428.469208] Hardware name: HP Grunt/Grunt, BIOS Google_Grunt.11031.169.0 06/24/2021
> [  428.469219] Workqueue: events_unbound async_run_entry_fn
> [  428.469230] RIP: 0010:kfree+0x319/0x31b
> [  428.469235] Code: f9 fb ff 48 89 df 44 89 f6 48 83 c4 20 5b 41 5c 41 5d 41 5e 41 5f 5d e9 96 01 ff ff e8 6d 43 d5 ff e9 59 fd ff ff 0f 0b 0f 0b <0f> 0b 0f 1f 44 00 00 55 48 89 e5 41 57 41 56 41 54 53 48 83 e4 f0
> [  428.469241] RSP: 0018:ffffa1fac015fc30 EFLAGS: 00010246
> [  428.469247] RAX: ffffedb10419d108 RBX: ffff8c05262b0000 RCX: ffffedb10498ac00
> [  428.469252] RDX: ffff8c04a8c07000 RSI: 0000000000000000 RDI: ffff8c05262b0000
> [  428.469256] RBP: ffffa1fac015fc78 R08: 0000000000000000 R09: ffffffffc04eed71
> [  428.469260] R10: ffffedb10498ac00 R11: 0000000000000000 R12: ffff8c0508600f80
> [  428.469265] R13: ffff8c0508603ca8 R14: 0000000000000000 R15: ffff8c0508602380
> [  428.469271] FS:  0000000000000000(0000) GS:ffff8c052ad00000(0000) knlGS:0000000000000000
> [  428.469276] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  428.469280] CR2: 00005c940ab31a48 CR3: 000000011c764000 CR4: 00000000001506e0
> [  428.469285] Call Trace:
> [  428.469295]  ? dma_free_attrs+0x5f/0x7d
> [  428.469320]  ath10k_core_stop+0x5b/0x6f [ath10k_core 806151abc028dad4ca5e05ccf91f5120f8babc6b]
> [  428.469336]  ath10k_halt+0x126/0x177 [ath10k_core 806151abc028dad4ca5e05ccf91f5120f8babc6b]
> [  428.469352]  ath10k_stop+0x41/0x7e [ath10k_core 806151abc028dad4ca5e05ccf91f5120f8babc6b]
> [  428.469387]  drv_stop+0x88/0x10e [mac80211 c248faf7eea878afb2c5aad3740bc0315b08197b]
> [  428.469410]  __ieee80211_suspend+0x297/0x411 [mac80211 c248faf7eea878afb2c5aad3740bc0315b08197b]
> [  428.469441]  rdev_suspend+0x6e/0xd0 [cfg80211 b5e6ab05f100fefb9c12e1210da0d62f6254b594]
> [  428.469462]  wiphy_suspend+0xb1/0x105 [cfg80211 b5e6ab05f100fefb9c12e1210da0d62f6254b594]
> [  428.469483]  ? name_show+0x2d/0x2d [cfg80211 b5e6ab05f100fefb9c12e1210da0d62f6254b594]
> [  428.469490]  dpm_run_callback+0x8c/0x126
> [  428.469511]  ? name_show+0x2d/0x2d [cfg80211 b5e6ab05f100fefb9c12e1210da0d62f6254b594]
> [  428.469517]  __device_suspend+0x2e7/0x41b
> [  428.469523]  async_suspend+0x1f/0x93
> [  428.469529]  async_run_entry_fn+0x3d/0xd1
> [  428.469535]  process_one_work+0x1b1/0x329
> [  428.469541]  worker_thread+0x213/0x372
> [  428.469547]  kthread+0x150/0x15f
> [  428.469552]  ? pr_cont_work+0x58/0x58
> [  428.469558]  ? kthread_blkcg+0x31/0x31
>
> Tested-on: QCA6174 hw3.2 PCI WLAN.RM.4.4.1-00110-QCARMSWP-1
> Signed-off-by: Wen Gong <quic_wgong at quicinc.com>
> ---
> v2:
>     1. change commit log
>     2. remove NULL check before memory free since NULL is OK for dma_free_coherent()/kfree()
>
>   drivers/net/wireless/ath/ath10k/htt_rx.c | 6 ++++++
>   1 file changed, 6 insertions(+)
>
> diff --git a/drivers/net/wireless/ath/ath10k/htt_rx.c b/drivers/net/wireless/ath/ath10k/htt_rx.c
> index 771252dd6d4e..f6645c7c55c2 100644
> --- a/drivers/net/wireless/ath/ath10k/htt_rx.c
> +++ b/drivers/net/wireless/ath/ath10k/htt_rx.c
> @@ -301,12 +301,16 @@ void ath10k_htt_rx_free(struct ath10k_htt *htt)
>   			  ath10k_htt_get_vaddr_ring(htt),
>   			  htt->rx_ring.base_paddr);
>   
> +	ath10k_htt_config_paddrs_ring(htt, NULL);
> +
>   	dma_free_coherent(htt->ar->dev,
>   			  sizeof(*htt->rx_ring.alloc_idx.vaddr),
>   			  htt->rx_ring.alloc_idx.vaddr,
>   			  htt->rx_ring.alloc_idx.paddr);
> +	htt->rx_ring.alloc_idx.vaddr = NULL;
>   
>   	kfree(htt->rx_ring.netbufs_ring);
> +	htt->rx_ring.netbufs_ring = NULL;
>   }
>   
>   static inline struct sk_buff *ath10k_htt_rx_netbuf_pop(struct ath10k_htt *htt)
> @@ -846,8 +850,10 @@ int ath10k_htt_rx_alloc(struct ath10k_htt *htt)
>   			  ath10k_htt_get_rx_ring_size(htt),
>   			  vaddr_ring,
>   			  htt->rx_ring.base_paddr);
> +	ath10k_htt_config_paddrs_ring(htt, NULL);
>   err_dma_ring:
>   	kfree(htt->rx_ring.netbufs_ring);
> +	htt->rx_ring.netbufs_ring = NULL;
>   err_netbuf:
>   	return -ENOMEM;
>   }
>
> base-commit: 748b34786d1c96e758862d8e8577106ccde6515a