[v2.6.34-stable 073/213] b43legacy: Fix crash on unload when firmware not available

From: Paul Gortmaker
Date: Wed Feb 05 2014 - 15:56:31 EST

From: Larry Finger <Larry.Finger@xxxxxxxxxxxx>

-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
If you see a problem with using this for longterm, please comment.
-------------------

commit 2d838bb608e2d1f6cb4280e76748cb812dc822e7 upstream.

When b43legacy is loaded without the firmware being available, a following
unload generates a kernel NULL pointer dereference BUG as follows:

[ 214.330789] BUG: unable to handle kernel NULL pointer dereference at 0000004c
[ 214.330997] IP: [<c104c395>] drain_workqueue+0x15/0x170
[ 214.331179] *pde = 00000000
[ 214.331311] Oops: 0000 [#1] SMP
[ 214.331471] Modules linked in: b43legacy(-) ssb pcmcia mac80211 cfg80211 af_packet mperf arc4 ppdev sr_mod cdrom sg shpchp yenta_socket pcmcia_rsrc pci_hotplug pcmcia_core battery parport_pc parport floppy container ac button edd autofs4 ohci_hcd ehci_hcd usbcore usb_common thermal processor scsi_dh_rdac scsi_dh_hp_sw scsi_dh_emc scsi_dh_alua scsi_dh fan thermal_sys hwmon ata_generic pata_ali libata [last unloaded: cfg80211]
[ 214.333421] Pid: 3639, comm: modprobe Not tainted 3.6.0-rc6-wl+ #163 Source Technology VIC 9921/ALI Based Notebook
[ 214.333580] EIP: 0060:[<c104c395>] EFLAGS: 00010246 CPU: 0
[ 214.333687] EIP is at drain_workqueue+0x15/0x170
[ 214.333788] EAX: c162ac40 EBX: cdfb8360 ECX: 0000002a EDX: 00002a2a
[ 214.333890] ESI: 00000000 EDI: 00000000 EBP: cd767e7c ESP: cd767e5c
[ 214.333957] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
[ 214.333957] CR0: 8005003b CR2: 0000004c CR3: 0c96a000 CR4: 00000090
[ 214.333957] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
[ 214.333957] DR6: ffff0ff0 DR7: 00000400
[ 214.333957] Process modprobe (pid: 3639, ti=cd766000 task=cf802e90 task.ti=cd766000)
[ 214.333957] Stack:
[ 214.333957] 00000292 cd767e74 c12c5e09 00000296 00000296 cdfb8360 cdfb9220 00000000
[ 214.333957] cd767e90 c104c4fd cdfb8360 cdfb9220 cd682800 cd767ea4 d0c10184 cd682800
[ 214.333957] cd767ea4 cba31064 cd767eb8 d0867908 cba31064 d087e09c cd96f034 cd767ec4
[ 214.333957] Call Trace:
[ 214.333957] [<c12c5e09>] ? skb_dequeue+0x49/0x60
[ 214.333957] [<c104c4fd>] destroy_workqueue+0xd/0x150
[ 214.333957] [<d0c10184>] ieee80211_unregister_hw+0xc4/0x100 [mac80211]
[ 214.333957] [<d0867908>] b43legacy_remove+0x78/0x80 [b43legacy]
[ 214.333957] [<d083654d>] ssb_device_remove+0x1d/0x30 [ssb]
[ 214.333957] [<c126f15a>] __device_release_driver+0x5a/0xb0
[ 214.333957] [<c126fb07>] driver_detach+0x87/0x90
[ 214.333957] [<c126ef4c>] bus_remove_driver+0x6c/0xe0
[ 214.333957] [<c1270120>] driver_unregister+0x40/0x70
[ 214.333957] [<d083686b>] ssb_driver_unregister+0xb/0x10 [ssb]
[ 214.333957] [<d087c488>] b43legacy_exit+0xd/0xf [b43legacy]
[ 214.333957] [<c1089dde>] sys_delete_module+0x14e/0x2b0
[ 214.333957] [<c110a4a7>] ? vfs_write+0xf7/0x150
[ 214.333957] [<c1240050>] ? tty_write_lock+0x50/0x50
[ 214.333957] [<c110a6f8>] ? sys_write+0x38/0x70
[ 214.333957] [<c1397c55>] syscall_call+0x7/0xb
[ 214.333957] Code: bc 27 00 00 00 00 a1 74 61 56 c1 55 89 e5 e8 a3 fc ff ff 5d c3 90 55 89 e5 57 56 89 c6 53 b8 40 ac 62 c1 83 ec 14 e8 bb b7 34 00 <8b> 46 4c 8d 50 01 85 c0 89 56 4c 75 03 83 0e 40 80 05 40 ac 62
[ 214.333957] EIP: [<c104c395>] drain_workqueue+0x15/0x170 SS:ESP 0068:cd767e5c
[ 214.333957] CR2: 000000000000004c
[ 214.341110] ---[ end trace c7e90ec026d875a6 ]---Index: wireless-testing/drivers/net/wireless/b43legacy/main.c

The problem is fixed by making certain that the ucode pointer is not NULL
before deregistering the driver in mac80211.

Signed-off-by: Larry Finger <Larry.Finger@xxxxxxxxxxxx>
Signed-off-by: John W. Linville <linville@xxxxxxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
drivers/net/wireless/b43legacy/main.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/net/wireless/b43legacy/main.c b/drivers/net/wireless/b43legacy/main.c
index bb2dd9329aa0..40112d49ec3e 100644
--- a/drivers/net/wireless/b43legacy/main.c
+++ b/drivers/net/wireless/b43legacy/main.c
@@ -3849,6 +3849,8 @@ static void b43legacy_remove(struct ssb_device *dev)
cancel_work_sync(&wldev->restart_work);

B43legacy_WARN_ON(!wl);
+ if (!wldev->fw.ucode)
+ return; /* NULL if fw never loaded */
if (wl->current_dev == wldev)
ieee80211_unregister_hw(wl->hw);

--
1.8.5.2

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/