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This change has been made by an automated script, maintained by the
Ubuntu Kernel Team.
** Changed in: linux (Ubuntu)
Status: New => Incomplete
** Tags added: bionic
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https://bugs.launchpad.net/bugs/1791893
Title:
Trailing garbage data when sending on an AF_PACKET socket
Status in linux package in Ubuntu:
Incomplete
Bug description:
When sending an Ethernet frame on an packet socket (AF_PACKET,
SOCK_RAW), an additional 14 bytes of trailing data is sent on the
interface. The extra 14 bytes are present regardless of the packet
size. The extra data could be garbage/uninitialised kernel memory.
Expected result:
The raw Ethernet frame is sent on the interface.
Actual result:
The raw Ethernet frame plus an additional 14 bytes of unknown data is sent on
the interface.
Steps to reproduce:
The attached test program inject.c can be used to reproduce the issue.
# In window 1. Send an EAP packet without any payload.
gcc inject.c -o inject
sudo ./inject lo
# Simultaneously in window 2. Tcpdump shows a payload of 14 bytes.
sudo tcpdump -i lo -enlx
07:45:45.005652 02:00:00:00:00:01 > 02:00:00:00:00:00, ethertype EAPOL
(0x888e), length 28: EAP packet (0) v64, len 0
0x0000: 4000 0000 0000 0000 4000 0000 0000
Running strace on the "inject" program shows that send(2) is indeed
called with the correct buffer size. The extra 14 bytes appear to be
added by the kernel, and this might leak kernel memory.
Ubuntu release:
Ubuntu 18.04.1 LTS
Package version:
4.15.0-33.36
The issue could not be reproduced on linux-image-4.15.0-22-generic or
linux-image-4.15.0-23-generic.
uname -a:
Linux ubuntu 4.15.0-33-generic #36-Ubuntu SMP Wed Aug 15 16:00:05 UTC 2018
x86_64 x86_64 x86_64 GNU/Linux
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