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Message-ID: <20250508230254.GG1827@brightrain.aerifal.cx>
Date: Thu, 8 May 2025 19:02:54 -0400
From: Rich Felker <dalias@...c.org>
To: whistle@...l.ustc.edu.cn
Cc: musl@...ts.openwall.com
Subject: Re: Potential Injection Vulnerability in _vsyslog Function
On Thu, May 08, 2025 at 11:14:55PM +0800, whistle@...l.ustc.edu.cn wrote:
> In the current _vsyslog function, if the log contains characters
> like \r or \n, according to CWE-93: Improper Neutralization of CRLF
> Sequences ('CRLF Injection'), this could potentially lead to an
> injection vulnerability.
>
>
> When using musl, would it be safer to explicitly handle \r and \n
> here as an extra security measure?
I don't think there's any reason we should be munging the contents of
the log message here. The syslogd receiving the datagram is free to
reject embedded newlines (meaning \n; \r is completely irrelevant here
AFAICT) or store them in some storage-backend-specific way. If it
stores them in a manner where they can be misinterpreted as the start
of a new log record with different process credentials, that seems
like a weakness in the syslogd not in the libc. Especially since
someone wanting to do that could just write their own client sending
the datagrams with embedded newlines to /dev/log, no?
Rich
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