Public bug reported:
Upstream linux kernel implemented ring parameter boundaries check in commit:
37e2d99b59c4 ("ethtool: Ensure new ring parameters are within bounds during
SRINGPARAM")
(see link
https://patchwork.ozlabs.org/project/netdev/patch/1515420026-11970-2
-git-send-email-tar...@mellanox.com/)
Due to this commit, the community doesn't allow ring parameter boundary
checks in driver code.
The Bionic ubuntu kernel does not include this patch. And some network drivers
rely on this patch for
boundary checking of ring params.
This causes bugs in case a ringparam was given an illegal value.
Reproduction steps in AWS:
1. Create new c5.4xlarge instance with the ubuntu 18.04 official ami (uses the
ENA network driver) and update to latest kernel using apt-get dist-upgrade and
reboot for the new kernel to load.
2. Run ethtool -g ens5
output:
Ring parameters for ens5:
Pre-set maximums:
RX: 16384
RX Mini: 0
RX Jumbo: 0
TX: 1024
Current hardware settings:
RX: 1024
RX Mini: 0
RX Jumbo: 0
TX: 1024
3. Change the tx ring size to a legal number within boundaries - works!
4. Change the tx ring size to an illegal number such as 2048 with the command -
sudo ethtool -G ens5 tx 2048.
Expected behavior - operation not allowed
Actual behavior - causes a crash of the driver since boundaries are not checked
by ethtool.
Proposed fix - include the above commit 37e2d99b59c4 ("ethtool: Ensure
new ring parameters are within bounds during SRINGPARAM") in bionic (and
probably other ubuntu releases as well)
More data about the machine where the bug occured:
ubuntu@ip-172-31-80-28:~/bionic$ lsb_release -rd
Description: Ubuntu 18.04.4 LTS
Release: 18.04
ubuntu@ip-172-31-80-28:~/bionic$ uname -r
4.15.0-1065-aws
** Affects: ubuntu
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1874444
Title:
Bionic ubuntu ethtool doesn't check ring parameters boundaries
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