It's not entirely clear how to treat %NULL.
Clearly "match.interface-name=eth0" should not
match with an interface %NULL. But what about
"match.interface-name=!eth0"? It's now implemented
that negative matches still succeed against %NULL.
What about "match.interface-name=*"? That probably
should also match with %NULL. So we treat %NULL really
like "".
Against commit 11cd443448 ('iwd: Don't call IWD methods when device
unmanaged'), we got this backtrace:
#0 0x00007f1c164069f1 in __strnlen_avx2 () at ../sysdeps/x86_64/multiarch/strlen-avx2.S:62
#1 0x00007f1c1637ac9e in __fnmatch (pattern=<optimized out>, string=<optimized out>, string@entry=0x0, flags=flags@entry=0) at fnmatch.c:379
p = 0x0
res = <optimized out>
orig_pattern = <optimized out>
n = <optimized out>
wpattern = 0x7fff8d860730 L"pci-0000:03:00.0"
ps = {__count = 0, __value = {__wch = 0, __wchb = "\000\000\000"}}
wpattern_malloc = 0x0
wstring_malloc = 0x0
wstring = <optimized out>
alloca_used = 80
__PRETTY_FUNCTION__ = "__fnmatch"
#2 0x0000564484a978bf in nm_wildcard_match_check (str=0x0, patterns=<optimized out>, num_patterns=<optimized out>) at src/core/nm-core-utils.c:1959
is_inverted = 0
is_mandatory = 0
match = <optimized out>
p = 0x564486c43fa0 "pci-0000:03:00.0"
has_optional = 0
has_any_optional = 0
i = <optimized out>
#3 0x0000564484bf4797 in check_connection_compatible (self=<optimized out>, connection=<optimized out>, error=0x0) at src/core/devices/nm-device.c:7499
patterns = <optimized out>
device_driver = 0x564486c76bd0 "veth"
num_patterns = 1
priv = 0x564486cbe0b0
__func__ = "check_connection_compatible"
device_iface = <optimized out>
local = 0x564486c99a60
conn_iface = 0x0
klass = <optimized out>
s_match = 0x564486c63df0 [NMSettingMatch]
#4 0x0000564484c38491 in check_connection_compatible (device=0x564486cbe590 [NMDeviceVeth], connection=0x564486c6b160, error=0x0) at src/core/devices/nm-device-ethernet.c:348
self = 0x564486cbe590 [NMDeviceVeth]
s_wired = <optimized out>
Fixes: 3ced486f41 ('libnm/match: extend syntax for match patterns with '|', '&', '!' and '\\'')
https://bugzilla.redhat.com/show_bug.cgi?id=1942741
CVE-2021-20297
(cherry picked from commit 420784e342)
(cherry picked from commit eaba0b4845)
(cherry picked from commit 16e5b307a3)
32566dd5e1