netdev - Memory corruption with r8169 across several device revisions and kernels

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Date:   Sat, 20 Jan 2018 21:18:54 +0100
From:   Oliver Freyermuth <o.freyermuth@...glemail.com>
To:     netdev@...r.kernel.org
Subject: Memory corruption with r8169 across several device revisions and
 kernels

Dear network experts,

please redirect me if this is the wrong place. 

I have reproduced the following issue across three devices with different Realtek card revisions
and different Distros (Debian 9, Ubuntu 17.04, Gentoo with kernels 4.9, 4.11.3, 4.14.12). 

It's safely reproducible with at least:
Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 06)
Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 12)

Memory corruption at physical addresses either in low memory or kernel memory or user space memory occurs when reading from:
/proc/self/net/dev
The physical memory addresses which get corrupted change with each boot of the system,
and also appear to change with each reload of the kernel module (I have only one data point on that). 

To reproduce, execute:
$ while true; do cat /proc/self/net/dev > /dev/null; done
and in parallel, scan memory for corruption, e.g.
$ memtester 15G
Of course, one should try to map all system memory here. 
It usually shows up in the first loop iteration if the "while" loop is executed in parallel. 

Depending on the actual memory being corrupted, it may also become visible via
Corrupted low memory at ffff88000000b000 (b000 phys) = 0016e109
in klog, if the low memory corruption scanning is activated. 

The values found in overwritten memory match those contained in /proc/self/net/dev for the realtek ethernet device. 

Unloading r8169 or disabling the card in bios "fixes" this issue. 

I have already ended up with two corrupted btrfs filesystems due to this issue, and many segfaults in userspace. 

Please include me directly in replies, I may not stay subscribed to the list. 

Cheers,
	Oliver