Dear Kernel hackers,
a small follow up: The problem is reproducible with an Ubuntu 17.04 live
system.
It vanishes as soon as I disable the Realtek-network-card in the UEFI, put in
an Intel card, and use that.
So the problem must either be a kernel bug (then most likely for r8168 only),
or a very strange firmware / hardware issue of this specific card.
If you have any further suggestions to debug this (if it's a kernel bug, I
would guess it's exploitable since it allows writes to non-userspace memory),
please let me know.
Cheers and all the best,
Oliver
Am 26.05.2017 um 13:26 schrieb Oliver Freyermuth:
> Dear Kernel hackers,
>
> I have a machine with a self-built, non-tainted kernel, which exhibits memory
> corruption as soon as I execute
> while true; do cat /proc/self/net/dev > /dev/null; done
> as normal user.
>
> I am running 4.11.3 (almost vanilla, only Gentoo patches in) on mostly
> standard hardware (Intel CPU + GPU).
> I can also reproduce with 4.9 on that machine.
> RAM has already been exchanged. Due to a BIOS bug, the machine needs
> "iommu=soft" as kernel parameter, but nothing special otherwise.
>
> The corruption appears in two ways:
> Often via:
> Corrupted low memory at ffff88000000b000 (b000 phys) = 0016e109
> Almost every time visible via:
> memtester 15G
> (machine has 16 G).
>
> Checking the output of memtester, the values it finds match with the content
> of the numbers in:
> /proc/self/net/dev
>
> After each boot, it seems the memory page where the corruption appears is
> slightly changed, it is usually in the region around 0x94F6000 (physical
> address).
>
> I have attached my kernel config, gzipped.
>
> I would be very grateful for any advice on how to debug this further - it
> does not really look like a hardware issue to me anymore,
> but if it could be, please enlighten me.
>
> Please include me in replies, as I am not subscribed to the list.
>
> In case relevant, my network controller is:
> 02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd.
> RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 06)
>
> Thanks and all the best,
> Oliver Freyermuth
>
