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Bug 906113 (CVE-2023-31137) - <net-dns/maradns-3.5.0036: integer underflow vulnerability
Summary: <net-dns/maradns-3.5.0036: integer underflow vulnerability
Alias: CVE-2023-31137
Product: Gentoo Security
Classification: Unclassified
Component: Vulnerabilities (show other bugs)
Hardware: All Linux
: Normal minor (vote)
Assignee: Gentoo Security
Whiteboard: B3 [stable?]
Keywords: PullRequest
Depends on:
Reported: 2023-05-11 04:45 UTC by John Helmert III
Modified: 2024-02-09 14:29 UTC (History)
1 user (show)

See Also:
Package list:
Runtime testing required: ---


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Description John Helmert III archtester Gentoo Infrastructure gentoo-dev Security 2023-05-11 04:45:07 UTC

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:
Comment 1 Larry the Git Cow gentoo-dev 2024-02-09 13:47:37 UTC
The bug has been referenced in the following commit(s):

commit 73937e86b92dcf813bf021a83451e2ae4dbc423c
Author:     Christopher Fore <>
AuthorDate: 2024-01-20 16:34:59 +0000
Commit:     Joonas Niilola <>
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
    Signed-off-by: Christopher Fore <>
    Signed-off-by: Joonas Niilola <>

 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(-)