https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=c8168e888eb42870e10e6d9d96609d4c3cf2e06d
Fixes this.
A NULL pointer is only ever passed when the array size is zero, and real
world qsort() implementations seem to behave in a sensible manner under
those conditions, so this isn't a problem that's going to inconvenience
anyone. Good to get it right anyway.
Thanks for the report.
Simon.
On 09.03.2026 13:24, fuyulai2024 wrote:
## Description
```
dnsmasq attempts to pass a null pointer (NULL) to a function in the
domain-match.c file at line 82,
while the function's parameter is declared as nonnull (i.e., it must not
be NULL).
As declared in the function's parameter attributes in C, the function
expects to receive a non-null pointer.
However, dnsmasq passes a null pointer during the function call, which
may lead to a program crash.
```
## Running Environment
```
Distributor ID: Ubuntu
Description: Ubuntu 20.04.6 LTS
Release: 20.04
Codename: focal
```
## Protocol Implementation Version
```
root@cbf1f9c04f26:~/dnsmasq/src# git log --oneline
ee09f06 (HEAD -> master, origin/master, origin/HEAD) Optimise tftp.
1e83316 (tag: v2.92test21) Formatting.
9a566c0 Tweak recently altered TFTP code.
```
## Build
```
export CC=afl-clang-fast
export CXX=afl-clang-fast++
make COPTS="-g -fsanitize=address,undefined -fno-omit-frame-pointer"
LDFLAGS="-fsanitize=address,undefined"
```
## Logs
```
root@cbf1f9c04f26:~/dnsmasq/src# ./dnsmasq -p 5353 -d -C /root/dnsmasq/
dnsmasq.conf -8 /var/log/dnsmasq/dnsmasq.log
pc_guard: [INIT] bitmap has been allocted from addr 8696316 to 8914568
[ 54563 bits - ratio: 100%]
lucky: [INIT] bitmap has been allocted from idx 1 to 54563
lucky: [INIT]inital edge cnt: 2119
Shared Memory: /dev/shm/cov_bitmap_dns
dnsmasq: started, version 2.92test21-1-gee09f06 cachesize 150
dnsmasq: compile time options: IPv6 GNU-getopt no-DBus no-UBus no-i18n
no-IDN DHCP DHCPv6 no-Lua TFTP no-conntrack ipset no-nftset auth no-
DNSSEC loop-detect inotify dumpfile
domain-match.c:82:9: runtime error: null pointer passed as argument 1,
which is declared to never be null
/usr/include/stdlib.h:831:30: note: nonnull attribute specified here
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior domain-
match.c:82:9 in
dnsmasq: reading /etc/resolv.conf
dnsmasq: using nameserver 192.168.65.7#53
dnsmasq: read /etc/hosts - 9 names
```
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