[Xenomai] rthal_strncpy_from_user bug

C Smith csmithquestions at gmail.com
Sat Dec 22 09:34:34 CET 2018


I can confirm that this is not fixed in Xenomai 2.6.5. (I too am on that
branch because of legacy code). I found that certain I5 processors generate
the memory exception during cpy_from_user() calls, and certain I5
processors don't. I successfully worked around the problem, as Henning
Schild explains, by disabling CONFIG_SMAP in the kernel config. I am on
kernel 3.18.20 and in order to reveal that setting in 'make menuconfig' in
the processor features - you'll need to first enable 'kernel debugging' and
also choose 'Embedded' as well.

-C Smith

On Thu, Sep 29, 2016 at 3:49 AM Henning Schild <henning.schild at siemens.com>
wrote:

> Am Wed, 28 Sep 2016 13:12:12 +0200
> schrieb Leopold Palomo-Avellaneda <leo at alaxarxa.net>:
>
> > Hi,
> >
> >
> > I'm trapped between 2.6.x and 3.x versions. The question to not
> > boring you is that I'm having a lot of problems with this soft 3.x so
> > I try to go back again to 2.6.
> >
> > However, I need to use a modern hardware (new development) and 2.6
> > have some issues especially rtnet that doesn't work without some
> > patch with kernels greater than 3.17 (or at least I'm not able to).
> >
> > After solving some other issues my tests fails with some ugly message
> > (killed!!!!)
> >
> > [ 5761.024502] RIP  [<ffffffff8143079d>]
> > rthal_strncpy_from_user+0xd/0x20 [ 5761.027017]  RSP
> > <ffff88045a493e20> [ 5761.029456] CR2: 000000000040445d
> > [ 5761.031859] ---[ end trace f092b4db2a9a9654 ]---
> > [ 5773.810428] BUG: unable to handle kernel paging request at
> > 000000000040445d [ 5773.812909] IP: [<ffffffff8143079d>]
> > rthal_strncpy_from_user+0xd/0x20 [ 5773.815389] PGD 45a00c067 PUD
> > 456d4e067 PMD 45aa42067 PTE 4517f5025 [ 5773.817864] Oops: 0001 [#16]
> > SMP [ 5773.820293] Modules linked in: rt_igb(O) rt_e1000e(O)
> > rt_loopback(O) rtcfg(O) rtudp(O) rtipv4(O) rtmac(O) rtpacket(O)
> > rtnet(O) ctr ccm binfmt_misc nfsd auth_rpcgss nfs_acl nfs lockd
> > fscache sunrpc nls_utf8 nls_cp437 vfat fat xeno_can_peak_pci
> > xeno_can_sja1000 xeno_can x86_pkg_temp_thermal coretemp kvm_intel kvm
> > peak_pci sja1000 joydev crc32_pclmul hid_generic usbhid
> > ghash_clmulni_intel aesni_intel ppdev aes_x86_64 lrw can_dev gf128mul
> > glue_helper xeno_rtdm snd_pcm snd_timer ablk_help
> >
> >
> > looking on the web, I have found that his issue was solved:
> >
> >
> http://git.xenomai.org/xenomai-jki.git/commit/?h=maintenance-2.6&id=2eceef4c62bc8d6b3713787c26882fdcd9b87842
> >
> > However, although it was on December 2015, 2.6.5 (July 2016) doesn't
> > have it.
> >
> > So, there's any reason why this patch was not pushed to 2.6.5?
>
> I guess the reason is that 2.6 is not officially maintained anymore, so
> patches like this one do not get backported. You should see if you can
> switch to 3.0 and solve your issues there!
>
> If that really is not an option, this particular problem can be
> addressed by disabling CONFIG_SMAP in your kernel. Or you could port
> the patch back to 2.6. If you do that post it here, might get accepted
> after all.
>
> Henning
>
> _______________________________________________
> Xenomai mailing list
> Xenomai at xenomai.org
> https://xenomai.org/mailman/listinfo/xenomai
>


More information about the Xenomai mailing list