[dpdk-dev] section mismatch warnings

[Michael Hu (NSBU)]

Thanks Neil and Sergio for your info.

The mismatch warning did not show up with normal kernel but in the kernel
with PAX grsecurity patches as PaX team enhanced writeable function
pointer detection in patches out in this link.
http://en.wikibooks.org/wiki/Grsecurity/Configuring_and_Installing_grsecuri
ty#Compilation_Differences
---
the extra section mismatches are due to my Pax changes, i explicitly
added detection for writeable function pointers which are potential
exploit targets, just to know how many of them there are. we've been
eliminating some of them already but this work will never finish.

as for what they are in general, a mismatch means an unwanted reference
from one section to another. say, accessing init code or data from
normal code/data is not good since init sections are freed up on boot,
so any reference to them must not exist from permanent sections.

---

To reproduce, you just need to patch any supported kernel with grsecurity
patches then compile dpdk with it.
https://grsecurity.net/download.php



Thanks,
Michael 






On 10/7/14 9:46 AM, "Neil Horman" <nhorman at tuxdriver.com> wrote:

>On Mon, Oct 06, 2014 at 06:42:04PM +0000, Michael Hu (NSBU) wrote:
>> Hi Everyone,
>> 
>> When we enable kernel config CONFIG_DEBUG_SECTION_MISMATCH=y and
>>compile DPDK 1.7 with 3.14.17 kernel + gcc 4.8.2, we got lots of
>>warnings like these.
>> Do we have plan to fix them? If so, please advise on which version.
>>Thanks.
>> 
>Seems erroneous.  These errors come from referencing symbols between
>incompatible sections (e.g. A static function reading a variable that is
>in an
>__initdata section).  But theres nothing like that going on in any of
>these
>symbols referenced below (and the kernel version shouldn't matter, as
>this is
>all dpdk internal).  It could be old objects in your build from a DPDK
>version
>where the symbols were in different sections.  Do a make clean; git clean
>-f -d
>Then reconfigure and rebuild.  I expect your issue will go away.
>
>Neil
>
>> 
>> 
>> == Build lib/librte_eal/linuxapp/kni
>> cut: /proc/version_signature: No such file or directory
>>   LD      
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/igb_uio/built-i
>>n.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/igb_uio/igb_uio
>>.o
>>   Building modules, stage 2.
>>   MODPOST 1 modules
>> WARNING: 
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/igb_uio/igb_uio
>>.o(.data+0x20): Section mismatch in reference from the variable
>>igbuio_pci_driver to the function .text:igbuio_pci_probe()
>> 
>> WARNING: 
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/igb_uio/igb_uio
>>.o(.data+0x28): Section mismatch in reference from the variable
>>igbuio_pci_driver to the function .text:igbuio_pci_remove()
>> 
>> WARNING: 
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/igb_uio/igb_uio
>>.o(.data+0x130): Section mismatch in reference from the variable
>>dev_attr_max_vfs to the function .text:show_max_vfs()
>> 
>> WARNING: 
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/igb_uio/igb_uio
>>.o(.data+0x138): Section mismatch in reference from the variable
>>dev_attr_max_vfs to the function .text:store_max_vfs()
>> 
>>   CC      
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/igb_uio/igb_uio
>>.mod.o
>>   LD [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/igb_uio/igb_uio
>>.ko
>> INSTALL-MODULE igb_uio.ko
>> 
>>   LD      
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/built-in.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/ixgbe_main.
>>o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/ixgbe_api.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/ixgbe_commo
>>n.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/ixgbe_ethto
>>ol.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/ixgbe_82599
>>.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/ixgbe_82598
>>.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/ixgbe_x540.
>>o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/ixgbe_phy.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/kcompat.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/e1000_82575
>>.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/e1000_i210.
>>o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/e1000_api.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/e1000_mac.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/e1000_manag
>>e.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/e1000_mbx.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/e1000_nvm.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/e1000_phy.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/igb_ethtool
>>.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/igb_hwmon.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/igb_main.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/igb_debugfs
>>.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/igb_param.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/igb_procfs.
>>o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/igb_vmdq.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/kni_misc.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/kni_net.o
>>   CC [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/kni_ethtool
>>.o
>>   LD [M]  
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/rte_kni.o
>> WARNING: 
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/rte_kni.o(.
>>data+0x20): Section mismatch in reference from the variable
>>ixgbe_ethtool_ops to the function .text:ixgbe_get_settings()
>> 
>> WARNING: 
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/rte_kni.o(.
>>data+0x28): Section mismatch in reference from the variable
>>ixgbe_ethtool_ops to the function .text:ixgbe_set_settings()
>> 
>> WARNING: 
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/rte_kni.o(.
>>data+0x30): Section mismatch in reference from the variable
>>ixgbe_ethtool_ops to the function .text:ixgbe_get_drvinfo()
>> 
>> WARNING: 
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/rte_kni.o(.
>>data+0x38): Section mismatch in reference from the variable
>>ixgbe_ethtool_ops to the function .text:ixgbe_get_regs_len()
>> 
>> WARNING: 
>>/git/Pktgen-DPDK/dpdk/build/build/lib/librte_eal/linuxapp/kni/rte_kni.o(.
>>data+0x40): Section mismatch in reference from the variable
>>ixgbe_ethtool_ops to the function .text:ixgbe_get_regs()
>> 
>> Thanks,
>> Michael
>> 
>> 
>>