[LTP] [PATCH] ltp_tpci.c: fix a null pointer
Yang Xu
xuyang2018.jy@cn.fujitsu.com
Fri Apr 10 07:21:38 CEST 2020
Hi Desnes
> Greetings Yang,thanks for the patch.
>
> On 3/18/20 1:55 AM, Yang Xu wrote:
>> Since commit 3dd286bdbee ("ltp_tpci.c: Update legacy code"),
>> it introduced a warning as below:
>> ../ltp_tpci.c: In function ‘probe_pci_dev’:
>> ../ltp_tpci.c:107:8: warning: ‘dev’ is used uninitialized in this
>> function [-Wuninitialized]
>> struct pci_dev *dev;
>> dev = pci_get_domain_bus_and_slot(pci_domain_nr(dev->bus), bus, slot)
>>
>> This will lead to system crash when we run this case because it
>> triggers a null pointer.
>> Use 0 domain intead of pci_domain_nr.
>>
>> ps: I want to use a dymaic domain to fix it but failed. If someone know,
>> please tell me. Also, this case failed when merging this patch because
>> test 13 (test_assign_resources) report no space error as below:
>> [754930.757585] ltp_tpci: test-case 13
>> [754930.757585] ltp_tpci: assign resources
>> [754930.757585] ltp_tpci: assign resource #0
>> [754930.757586] ltp_tpci: name = 0000:00:08.0, flags = 262401, start
>> 0xc140, end 0xc17f
>> [754930.757586] ltp_tpci: assign resource #1
>> [754930.757587] ltp_tpci: name = 0000:00:08.0, flags = 262656, start
>> 0xfebd7000, end 0xfebd7fff
>> [754930.757587] ltp_tpci: assign resource #2
>> [754930.757587] ltp_tpci: name = 0000:00:08.0, flags = 0, start 0x0,
>> end 0x0
>> [754930.757588] ltp_tpci: assign resource #3
>> [754930.757588] ltp_tpci: name = 0000:00:08.0, flags = 0, start 0x0,
>> end 0x0
>> [754930.757588] ltp_tpci: assign resource #4
>> [754930.757589] ltp_tpci: name = 0000:00:08.0, flags = 538190348,
>> start 0xfe80c000, end 0xfe80ffff
>> [754930.757593] virtio-pci 0000:00:08.0: BAR 4: no space for [mem size
>> 0x00004000 64bit pref]
>> [754930.757594] virtio-pci 0000:00:08.0: BAR 4: failed to assign [mem
>> size 0x00004000 64bit pref
>>
>> Fixes: 3dd286b ("ltp_tpci.c: Update legacy code")
>> Signed-off-by: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
>> ---
>> testcases/kernel/device-drivers/pci/tpci_kernel/ltp_tpci.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git
>> a/testcases/kernel/device-drivers/pci/tpci_kernel/ltp_tpci.c
>> b/testcases/kernel/device-drivers/pci/tpci_kernel/ltp_tpci.c
>> index 7cbabfaa5..a57953db6 100644
>> --- a/testcases/kernel/device-drivers/pci/tpci_kernel/ltp_tpci.c
>> +++ b/testcases/kernel/device-drivers/pci/tpci_kernel/ltp_tpci.c
>> @@ -104,7 +104,7 @@ static int probe_pci_dev(unsigned int bus,
>> unsigned int slot)
>> ltp_pci.dev = NULL;
>> }
>> - dev = pci_get_domain_bus_and_slot(pci_domain_nr(dev->bus), bus,
>> slot);
>> + dev = pci_get_domain_bus_and_slot(0, bus, slot);
>> if (!dev || !dev->driver)
>> return -ENODEV;
>
> I was about to post the same fix on the mailing list - just tested in
> powerpc arch and it looks good to me.
>
> It is safe to use 0 since function pci_get_bus_and_slot(unsigned int
> bus, unsigned int devfn) removed on kernel commit <5cf0c37a71da0f3>
> ("PCI: Remove pci_get_bus_and_slot() function") used to be a wrapper for
> pci_get_domain_bus_and_slot(0, bus, devfn).
Sorry for the late reply. Thanks for your review. I think this should be
added into commit message, so make this fix more clear.
Best Regards
Yang Xu
>
> Hence, this patch avoids the following Oops:
>
> =====
> [69614.978596] Unable to handle kernel paging request for data at
> address 0x00000010
> [69614.978602] Faulting instruction address: 0xd000000003c200a4
> [69614.978606] Oops: Kernel access of bad area, sig: 11 [#1]
> [69614.978609] LE SMP NR_CPUS=2048 NUMA PowerNV
> [69614.978613] Modules linked in: ltp_tpci(OE) vmac chacha20_generic
> poly1305_generic chacha20poly1305 snd_timer snd soundcore authenc pcrypt
> crypto_user sha3_generic salsa20_generic uinput can_raw can dummy veth
> n_gsm pps_ldisc ppp_synctty n_hdlc ppp_async ppp_generic slhc kvm_hv
> kvm_pr kvm binfmt_misc nfsv3 nfs_acl nfs lockd grace fscache tun brd
> vfat fat fuse overlay ext4 mbcache jbd2 loop sunrpc uio_pdrv_genirq ses
> xts ipmi_powernv enclosure ipmi_devintf uio scsi_transport_sas
> ibmpowernv ipmi_msghandler leds_powernv vmx_crypto powernv_rng
> powernv_op_panel ip_tables xfs libcrc32c sr_mod cdrom sd_mod sg ipr
> libata tg3 dm_mirror dm_region_hash dm_log dm_mod [last unloaded:
> ltp_block_dev]
> [69614.978653] Features: eBPF/sock
> [69614.978657] CPU: 1 PID: 2292176 Comm: tpci Kdump: loaded Tainted:
> G W OE --------- - - 4.18.0-187.el8.ppc64le #1
> [69614.978662] NIP: d000000003c200a4 LR: d000000003c2006c CTR:
> c000000000dc8c00
> [69614.978666] REGS: c0000004be437a20 TRAP: 0300 Tainted: G W
> OE --------- - - (4.18.0-187.el8.ppc64le)
> [69614.978670] MSR: 9000000000009033 <SF,HV,EE,ME,IR,DR,RI,LE> CR:
> 28002272 XER: 20000000
> [69614.978676] CFAR: c000000000008934 DAR: 0000000000000010 DSISR:
> 40000000 IRQMASK: 0
> GPR00: d000000003c2006c c0000004be437ca0 d000000003c2a300 0000000000000000
> GPR04: d000000003c214ba 0000000000000000 c0000007846448c9 0000000000000000
> GPR08: c0000004be437d04 0000000000000000 0000000000000000 0000000000000000
> GPR12: 0000000000002200 c0000007ffffee00 0000000000000000 0000000000000000
> GPR16: 0000000000000000 000000001001cf98 000000001001cf78 000000001001cff0
> GPR20: 000000001001d010 000000001001cf58 00007fff92643190 0000000010040530
> GPR24: 000000001001d108 000000001001cf48 c0000004be437df0 0000000000000001
> GPR28: fffffffffffffff2 0000000000000000 d000000003c22f80 0000000000000000
> [69614.978711] NIP [d000000003c200a4] sys_bus_slot+0x8c/0x170 [ltp_tpci]
> [69614.978715] LR [d000000003c2006c] sys_bus_slot+0x54/0x170 [ltp_tpci]
> [69614.978718] Call Trace:
> [69614.978721] [c0000004be437ca0] [d000000003c2006c]
> sys_bus_slot+0x54/0x170 [ltp_tpci] (unreliable)
> [69614.978727] [c0000004be437d40] [c0000000008da5bc]
> dev_attr_store+0x3c/0x60
> [69614.978732] [c0000004be437d60] [c0000000005fb908]
> sysfs_kf_write+0x68/0x80
> [69614.978736] [c0000004be437d80] [c0000000005f9fb4]
> kernfs_fop_write+0x104/0x270
> [69614.978741] [c0000004be437dd0] [c0000000004ff624] sys_write+0x134/0x3a0
> [69614.978745] [c0000004be437e30] [c00000000000b388] system_call+0x5c/0x70
> [69614.978748] Instruction dump:
> [69614.978751] ebde8010 80a10064 e87e0000 78bdc622 54bf063e 2fa30000
> 419e0014 48000e89
> [69614.978757] e8410018 39200000 f93e0000 39200000 <e8690010> 48000dd1
> e8410018 7fe5fb78
> [69614.978764] ---[ end trace 414b1270f579351f ]---
> =====
>
> Reviewed-by: Desnes A. Nunes do Rosario <desnesn@linux.ibm.com>
>
>>
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