Bug 906113 (CVE-2023-31137) – <net-dns/maradns-3.5.0036: integer underflow vulnerability

• Product: Gentoo Security
• Status: CONFIRMED ---

[Description John Helmert III 2023-05-11 04:45:07 UTC]

CVE-2023-31137:

MaraDNS is open-source software that implements the Domain Name System (DNS). In version 3.5.0024 and prior, a remotely exploitable integer underflow vulnerability in the DNS packet decompression function allows an attacker to cause a Denial of Service by triggering an abnormal program termination.

The vulnerability exists in the `decomp_get_rddata` function within the `Decompress.c` file. When handling a DNS packet with an Answer RR of qtype 16 (TXT record) and any qclass, if the `rdlength` is smaller than `rdata`, the result of the line `Decompress.c:886` is a negative number `len = rdlength - total;`. This value is then passed to the `decomp_append_bytes` function without proper validation, causing the program to attempt to allocate a massive chunk of memory that is impossible to allocate. Consequently, the program exits with an error code of 64, causing a Denial of Service.

One proposed fix for this vulnerability is to patch `Decompress.c:887` by breaking `if(len <= 0)`, which has been incorporated in version 3.5.0036 via commit bab062bde40b2ae8a91eecd522e84d8b993bab58.

Patch is 3.5.0036: https://github.com/samboy/MaraDNS/commit/bab062bde40b2ae8a91eecd522e84d8b993bab58

[Comment 1 Larry the Git Cow 2024-02-09 13:47:37 UTC]

The bug has been referenced in the following commit(s):

https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=73937e86b92dcf813bf021a83451e2ae4dbc423c

commit 73937e86b92dcf813bf021a83451e2ae4dbc423c
Author:     Christopher Fore <[e-mail]>
AuthorDate: 2024-01-20 16:34:59 +0000
Commit:     Joonas Niilola <[e-mail]>
CommitDate: 2024-02-09 13:47:34 +0000

    net-dns/maradns: add 3.5.0036, security bump
    
    Rebased patch, removed fix_shebang due to the tool no longer being
    present.
    
    Bug: https://bugs.gentoo.org/906113
    Signed-off-by: Christopher Fore <[e-mail]>
    Closes: https://github.com/gentoo/gentoo/pull/34684
    Signed-off-by: Joonas Niilola <[e-mail]>

 net-dns/maradns/Manifest                           |  1 +
 net-dns/maradns/files/maradns-3.5.0022-flags.patch | 23 ++----
 net-dns/maradns/maradns-3.5.0036.ebuild            | 89 ++++++++++++++++++++++
 3 files changed, 97 insertions(+), 16 deletions(-)

[Comment 2 Larry the Git Cow 2025-01-02 12:15:11 UTC]

The bug has been referenced in the following commit(s):

https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=7e2c9c614fcadd30aa336d7a413fd7119f72c097

commit 7e2c9c614fcadd30aa336d7a413fd7119f72c097
Author:     Petr Vaněk <[e-mail]>
AuthorDate: 2025-01-02 12:01:39 +0000
Commit:     Petr Vaněk <[e-mail]>
CommitDate: 2025-01-02 12:14:28 +0000

    net-dns/maradns: drop 3.5.0022
    
    Bug: https://bugs.gentoo.org/906113
    Signed-off-by: Petr Vaněk <[e-mail]>

 net-dns/maradns/Manifest                           |  1 -
 net-dns/maradns/files/maradns-3.5.0022-flags.patch | 65 --------------
 net-dns/maradns/maradns-3.5.0022.ebuild            | 99 ----------------------
 3 files changed, 165 deletions(-)