linux-kernel - Re: [bisected] NULL pointer dereference in acpi_gpiochip

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Message-ID: <20140324181112.GN19349@intel.com>
Date:	Mon, 24 Mar 2014 20:11:12 +0200
From:	Mika Westerberg <mika.westerberg@...ux.intel.com>
To:	Sabrina Dubroca <sd@...asysnail.net>
Cc:	linux-gpio@...r.kernel.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [bisected] NULL pointer dereference in acpi_gpiochip_add (on
 modprobe ssb)

On Mon, Mar 24, 2014 at 08:00:33PM +0200, Mika Westerberg wrote:
> On Mon, Mar 24, 2014 at 04:49:44PM +0100, Sabrina Dubroca wrote:
> > Hi,
> > 
> > With next-20140324, I get the BUG below when I modprobe ssb.
> > I bisected it to aa92b6f689ac
> > "gpio / ACPI: Allocate ACPI specific data directly in acpi_gpiochip_add()"
> > 
> > The device that needs ssb is:
> > 0c:00.0 Network controller [0280]: Broadcom Corporation BCM4321 802.11a/b/g/n [14e4:4328] (rev 03)
> >         Subsystem: Dell Wireless 1500 Draft 802.11n WLAN Mini-card [1028:000a]
> >         Kernel driver in use: b43-pci-bridge
> >         Kernel modules: ssb
> > 
> > 
> > [   92.693606] ssb: Found chip with id 0x4321, rev 0x03 and package 0x00
> > [   92.693649] ssb: Core 0 found: ChipCommon (cc 0x800, rev 0x13, vendor 0x4243)
> > [   92.693675] ssb: Core 1 found: IEEE 802.11 (cc 0x812, rev 0x0C, vendor 0x4243)
> > [   92.693699] ssb: Core 2 found: PCI-E (cc 0x820, rev 0x04, vendor 0x4243)
> > [   92.693723] ssb: Core 3 found: PCI (cc 0x804, rev 0x0D, vendor 0x4243)
> > [   92.693746] ssb: Core 4 found: USB 1.1 Host (cc 0x817, rev 0x04, vendor 0x4243)
> > [   92.753554] BUG: unable to handle kernel NULL pointer dereference at 00000138
> > [   92.753760] IP: [<c126c2b3>] acpi_gpiochip_add+0x13/0x190
> > [   92.753901] *pde = 00000000 
> > [   92.753986] Oops: 0000 [#1] PREEMPT SMP 
> > [   92.754125] Modules linked in: ssb(+) mmc_core netconsole nouveau mxm_wmi i2c_algo_bit drm_kms_helper ttm drm joydev mousedev tg3 coretemp kvm_intel ptp pcmcia kvm pps_core libphy dell_laptop gpio_ich rfkill yenta_socket pcmcia_rsrc intel_agp intel_gtt iTCO_wdt iTCO_vendor_support dell_wmi sparse_keymap pcmcia_core evdev agpgart dcdbas snd_hda_codec_idt snd_hda_codec_generic microcode psmouse pcspkr i2c_i801 i2c_core serio_raw lpc_ich mfd_core acpi_cpufreq ac battery thermal button wmi snd_hda_intel snd_hda_controller snd_hda_codec snd_hwdep snd_pcm video snd_timer shpchp processor snd soundcore nfs lockd sunrpc ext4 crc16 mbcache jbd2 sd_mod sr_mod cdrom ata_generic pata_acpi ata_piix libata scsi_mod firewire_ohci firewire_core crc_itu_t uhci_hcd ehci_pci ehci_hcd usbcore usb_common
> > [   92.756833] CPU: 0 PID: 512 Comm: modprobe Tainted: G        W     3.14.0-rc7-next-20140324-t1 #24
> > [   92.756833] Hardware name: Dell Inc. Latitude D830                   /0UY141, BIOS A02 06/07/2007
> > [   92.756833] task: f5799900 ti: f543e000 task.ti: f543e000
> > [   92.756833] EIP: 0060:[<c126c2b3>] EFLAGS: 00010282 CPU: 0
> > [   92.756833] EIP is at acpi_gpiochip_add+0x13/0x190
> > [   92.756833] EAX: 00000000 EBX: f57824c4 ECX: 00000000 EDX: 00000000
> > [   92.756833] ESI: f57824c4 EDI: 00000010 EBP: f543fc54 ESP: f543fc40
> > [   92.756833]  DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
> > [   92.756833] CR0: 8005003b CR2: 00000138 CR3: 355f8000 CR4: 000007d0
> 
> To me looks like chip->dev is NULL. My understanding is that the GPIO core
> wants to have it non-NULL.

Actually gpiolib seems to handle ->dev as optional. Can you try this patch
instead? Thanks.

diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index bf0f8b476696..642b2bf3360e 100644
--- a/drivers/gpio/gpiolib-acpi.c
+++ b/drivers/gpio/gpiolib-acpi.c
@@ -501,6 +501,9 @@ void acpi_gpiochip_add(struct gpio_chip *chip)
 	acpi_handle handle;
 	acpi_status status;
 
+	if (!chip || !chip->dev)
+		return;
+
 	handle = ACPI_HANDLE(chip->dev);
 	if (!handle)
 		return;
@@ -531,6 +534,9 @@ void acpi_gpiochip_remove(struct gpio_chip *chip)
 	acpi_handle handle;
 	acpi_status status;
 
+	if (!chip || !chip->dev)
+		return;
+
 	handle = ACPI_HANDLE(chip->dev);
 	if (!handle)
 		return;
--
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