Re: Crash in netlink/sk_filter_trim_cap on ARMv7 on 4.18rc1

On Mon, Jun 25, 2018 at 9:48 AM, Daniel Borkmann [off-list ref] wrote:

On 06/24/2018 11:24 AM, Peter Robinson wrote:

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I'm seeing this netlink/sk_filter_trim_cap crash on ARMv7 across quite
a few ARMv7 platforms on Fedora with 4.18rc1. I've tested RPi2/RPi3
(doesn't happen on aarch64), AllWinner H3, BeagleBone and a few
others, both LPAE/normal kernels.

I'm a bit out of my depth in this part of the kernel but I'm wondering
if it's known, I couldn't find anything that looked obvious on a few
mailing lists.

Peter

Hi Peter

Could you provide symbolic information ?

I passed in through scripts/decode_stacktrace.sh is that what you were after:

[    8.673880] Internal error: Oops: a06 [#10] SMP ARM
[    8.673949] ---[ end trace 049df4786ea3140a ]---
[    8.678754] Modules linked in:
[    8.678766] CPU: 1 PID: 206 Comm: systemd-udevd Tainted: G      D
        4.18.0-0.rc1.git0.1.fc29.armv7hl+lpae #1
[    8.678769] Hardware name: Allwinner sun8i Family
[    8.678781] PC is at sk_filter_trim_cap ()
[    8.678790] LR is at   (null)
[    8.709463] pc : lr : psr: 60000013 ()
[    8.715722] sp : c996bd60  ip : 00000000  fp : 00000000
[    8.720939] r10: ee79dc00  r9 : c12c9f80  r8 : 00000000
[    8.726157] r7 : 00000000  r6 : 00000001  r5 : f1648000  r4 : 00000000
[    8.732674] r3 : 00000007  r2 : 00000000  r1 : 00000000  r0 : 00000000
[    8.739193] Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
[    8.746318] Control: 30c5387d  Table: 6e7bc880  DAC: ffe75ece
[    8.752055] Process systemd-udevd (pid: 206, stack limit = 0x(ptrval))
[    8.758574] Stack: (0xc996bd60 to 0xc996c000)

[...]

Should be fixed by (PR to Linus with fix is pending):

https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/commit/?id=9262478220eac908ae6e168c3df2c453c87e2da3

Unfortunately it's not, building against the git checkout of the first
failed Fedora kernel (see rc2 issue below) it has the same effect :-(

I thought it might have been [1] because it touches bits of that code
but if I trying with rc2 and that reverted I got no output at all,
checking the vanilla Fedora build from friday (so almost rc2) it
doesn't boot at all either so I've got a second thing to investigate.

Peter

[1] https://lkml.org/lkml/2018/4/29/30