ath11k: add ieee80211_unregister_hw to avoid kernel crash caused by NULL pointer

Wen Gong · gregkh · commit b5777172cce2 · 2021-04-07T15:00:07.000+02:00
[ Upstream commit 0d96968 ] When function return fail to __ath11k_mac_register after success called ieee80211_register_hw, then it set wiphy->dev.parent to NULL by SET_IEEE80211_DEV(ar->hw, NULL) in end of __ath11k_mac_register, then cfg80211_get_drvinfo will be called by below call stack, but the wiphy->dev.parent is NULL, so kernel crash. Call stack to cfg80211_get_drvinfo: NetworkManager 826 [001] 6696.731371: probe:cfg80211_get_drvinfo: (ffffffffc107d8f0) ffffffffc107d8f1 cfg80211_get_drvinfo+0x1 (/lib/modules/5.10.0-rc1-wt-ath+/kernel/net/wireless-back/cfg80211.ko) ffffffff9d8fc529 ethtool_get_drvinfo+0x99 (vmlinux) ffffffff9d90080e dev_ethtool+0x1dbe (vmlinux) ffffffff9d8b88f7 dev_ioctl+0xb7 (vmlinux) ffffffff9d8668de sock_do_ioctl+0xae (vmlinux) ffffffff9d866d60 sock_ioctl+0x350 (vmlinux) ffffffff9d2ca30e __x64_sys_ioctl+0x8e (vmlinux) ffffffff9da0dda3 do_syscall_64+0x33 (vmlinux) ffffffff9dc0008c entry_SYSCALL_64_after_hwframe+0x44 (vmlinux) 7feb5f673007 __GI___ioctl+0x7 (/lib/x86_64-linux-gnu/libc-2.23.so) 0 [unknown] ([unknown]) Code of cfg80211_get_drvinfo, the pdev which is wiphy->dev.parent is NULL when kernel crash: void cfg80211_get_drvinfo(struct net_device *dev, struct ethtool_drvinfo *info) { struct wireless_dev *wdev = dev->ieee80211_ptr; struct device *pdev = wiphy_dev(wdev->wiphy); if (pdev->driver) .... kernel crash log: [ 973.619550] ath11k_pci 0000:05:00.0: failed to perform regd update : -16 [ 973.619555] ath11k_pci 0000:05:00.0: ath11k regd update failed: -16 [ 973.619566] ath11k_pci 0000:05:00.0: failed register the radio with mac80211: -16 [ 973.619618] ath11k_pci 0000:05:00.0: failed to create pdev core: -16 [ 973.636035] BUG: kernel NULL pointer dereference, address: 0000000000000068 [ 973.636046] #PF: supervisor read access in kernel mode [ 973.636050] #PF: error_code(0x0000) - not-present page [ 973.636054] PGD 800000012452e067 P4D 800000012452e067 PUD 12452d067 PMD 0 [ 973.636064] Oops: 0000 [#1] SMP PTI [ 973.636072] CPU: 3 PID: 848 Comm: NetworkManager Kdump: loaded Tainted: G W OE 5.10.0-rc1-wt-ath+ #24 [ 973.636076] Hardware name: LENOVO 418065C/418065C, BIOS 83ET63WW (1.33 ) 07/29/2011 [ 973.636161] RIP: 0010:cfg80211_get_drvinfo+0x25/0xd0 [cfg80211] [ 973.636169] Code: e9 c9 fe ff ff 66 66 66 66 90 55 53 ba 20 00 00 00 48 8b af 08 03 00 00 48 89 f3 48 8d 7e 04 48 8b 45 00 48 8b 80 90 01 00 00 <48> 8b 40 68 48 85 c0 0f 84 8d 00 00 00 48 8b 30 e8 a6 cc 72 c7 48 [ 973.636174] RSP: 0018:ffffaafb4040bbe0 EFLAGS: 00010286 [ 973.636180] RAX: 0000000000000000 RBX: ffffaafb4040bbfc RCX: 0000000000000000 [ 973.636184] RDX: 0000000000000020 RSI: ffffaafb4040bbfc RDI: ffffaafb4040bc00 [ 973.636188] RBP: ffff8a84c9568950 R08: 722d302e30312e35 R09: 74612d74772d3163 [ 973.636192] R10: 3163722d302e3031 R11: 2b6874612d74772d R12: ffffaafb4040bbfc [ 973.636196] R13: 00007ffe453707c0 R14: ffff8a84c9568000 R15: 0000000000000000 [ 973.636202] FS: 00007fd3d179b940(0000) GS:ffff8a84fa2c0000(0000) knlGS:0000000000000000 [ 973.636206] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 973.636211] CR2: 0000000000000068 CR3: 00000001153b6002 CR4: 00000000000606e0 [ 973.636215] Call Trace: [ 973.636234] ethtool_get_drvinfo+0x99/0x1f0 [ 973.636246] dev_ethtool+0x1dbe/0x2be0 [ 973.636256] ? mntput_no_expire+0x35/0x220 [ 973.636264] ? inet_ioctl+0x1ce/0x200 [ 973.636274] ? tomoyo_path_number_perm+0x68/0x1d0 [ 973.636282] ? kmem_cache_alloc+0x3cb/0x430 [ 973.636290] ? dev_ioctl+0xb7/0x570 [ 973.636295] dev_ioctl+0xb7/0x570 [ 973.636307] sock_do_ioctl+0xae/0x150 [ 973.636315] ? sock_ioctl+0x350/0x3c0 [ 973.636319] sock_ioctl+0x350/0x3c0 [ 973.636332] ? __x64_sys_ioctl+0x8e/0xd0 [ 973.636339] ? dlci_ioctl_set+0x30/0x30 [ 973.636346] __x64_sys_ioctl+0x8e/0xd0 [ 973.636359] do_syscall_64+0x33/0x80 [ 973.636368] entry_SYSCALL_64_after_hwframe+0x44/0xa9 Sequence of function call when wlan load for success case when function __ath11k_mac_register return 0: kworker/u16:3-e 2922 [001] 6696.729734: probe:ieee80211_register_hw: (ffffffffc116ae60) kworker/u16:3-e 2922 [001] 6696.730210: probe:ieee80211_if_add: (ffffffffc1185cc0) NetworkManager 826 [001] 6696.731345: probe:ethtool_get_drvinfo: (ffffffff9d8fc490) NetworkManager 826 [001] 6696.731371: probe:cfg80211_get_drvinfo: (ffffffffc107d8f0) NetworkManager 826 [001] 6696.731639: probe:ethtool_get_drvinfo: (ffffffff9d8fc490) NetworkManager 826 [001] 6696.731653: probe:cfg80211_get_drvinfo: (ffffffffc107d8f0) NetworkManager 826 [001] 6696.732866: probe:ethtool_get_drvinfo: (ffffffff9d8fc490) NetworkManager 826 [001] 6696.732893: probe:cfg80211_get_drvinfo: (ffffffffc107d8f0) systemd-udevd 3850 [003] 6696.737199: probe:ethtool_get_drvinfo: (ffffffff9d8fc490) systemd-udevd 3850 [003] 6696.737226: probe:cfg80211_get_drvinfo: (ffffffffc107d8f0) NetworkManager 826 [000] 6696.759950: probe:ethtool_get_drvinfo: (ffffffff9d8fc490) NetworkManager 826 [000] 6696.759967: probe:cfg80211_get_drvinfo: (ffffffffc107d8f0) NetworkManager 826 [000] 6696.760057: probe:ethtool_get_drvinfo: (ffffffff9d8fc490) NetworkManager 826 [000] 6696.760062: probe:cfg80211_get_drvinfo: (ffffffffc107d8f0) After apply this patch, kernel crash gone, and below is the test case's sequence of function call and log when wlan load with fail by function ath11k_regd_update, and __ath11k_mac_register return fail: kworker/u16:5-e 192 [001] 215.174388: probe:ieee80211_register_hw: (ffffffffc1131e60) kworker/u16:5-e 192 [000] 215.174973: probe:ieee80211_if_add: (ffffffffc114ccc0) NetworkManager 846 [001] 215.175857: probe:ethtool_get_drvinfo: (ffffffff928fc490) kworker/u16:5-e 192 [000] 215.175867: probe:ieee80211_unregister_hw: (ffffffffc1131970) NetworkManager 846 [001] 215.175880: probe:cfg80211_get_drvinfo: (ffffffffc107f8f0) NetworkManager 846 [001] 215.176105: probe:ethtool_get_drvinfo: (ffffffff928fc490) NetworkManager 846 [001] 215.176118: probe:cfg80211_get_drvinfo: (ffffffffc107f8f0) [ 215.175859] ath11k_pci 0000:05:00.0: ath11k regd update failed: -16 NetworkManager 846 [001] 215.196420: probe:ethtool_get_drvinfo: (ffffffff928fc490) NetworkManager 846 [001] 215.196430: probe:cfg80211_get_drvinfo: (ffffffffc107f8f0) [ 215.258598] ath11k_pci 0000:05:00.0: failed register the radio with mac80211: -16 [ 215.258613] ath11k_pci 0000:05:00.0: failed to create pdev core: -16 When ath11k_regd_update or ath11k_debugfs_register return fail, function ieee80211_unregister_hw of mac80211 will be called, then it will wait untill cfg80211_get_drvinfo finished, the wiphy->dev.parent is not NULL at this moment, after that, it set wiphy->dev.parent to NULL by SET_IEEE80211_DEV(ar->hw, NULL) in end of __ath11k_mac_register, so not happen kernel crash. Tested-on: QCA6390 hw2.0 PCI WLAN.HST.1.0.1-01740-QCAHSTSWPLZ_V2_TO_X86-1 Signed-off-by: Wen Gong <wgong@codeaurora.org> Signed-off-by: Kalle Valo <kvalo@codeaurora.org> Link: https://lore.kernel.org/r/1608607824-16067-1-git-send-email-wgong@codeaurora.org Signed-off-by: Sasha Levin <sashal@kernel.org>
diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c
@@ -6317,17 +6317,20 @@ static int __ath11k_mac_register(struct ath11k *ar)
 	ret = ath11k_regd_update(ar, true);
 	if (ret) {
 		ath11k_err(ar->ab, "ath11k regd update failed: %d\n", ret);
-		goto err_free_if_combs;
+		goto err_unregister_hw;
 	}
 
 	ret = ath11k_debugfs_register(ar);
 	if (ret) {
 		ath11k_err(ar->ab, "debugfs registration failed: %d\n", ret);
-		goto err_free_if_combs;
+		goto err_unregister_hw;
 	}
 
 	return 0;
 
+err_unregister_hw:
+	ieee80211_unregister_hw(ar->hw);
+
 err_free_if_combs:
 	kfree(ar->hw->wiphy->iface_combinations[0].limits);
 	kfree(ar->hw->wiphy->iface_combinations);
