[PATCH 5.10 043/126] ath11k: add ieee80211_unregister_hw to avoid kernel crash caused by NULL pointer

Greg Kroah-Hartman
2021-04-05T09:10:46Z

From: Wen Gong <wgong@codeaurora.org>

[ Upstream commit 0d96968315d7ffbd70d608b29e9bea084210b96d ]

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>
---
drivers/net/wireless/ath/ath11k/mac.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c
index ee0edd918560..e9e6b0c4de22 100644
--- 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);
--
2.30.1