Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20230224135511.iunglqtcvpjeqgtv@gen2.localdomain>
Date: Fri, 24 Feb 2023 19:55:11 +0600
From: NRK <nrk@...root.org>
To: musl@...ts.openwall.com
Cc: Tamir Duberstein <tamird@...gle.com>
Subject: Re: undefined behavior in fread.c

On Fri, Feb 24, 2023 at 08:34:14AM -0500, Rich Felker wrote:
> Is there any indication that passing NULL as the first argument to
> fread is not itself undefined?

C99 says the following:

| If size or nmemb is zero, fread returns zero and the contents of the
| array and the state of the stream remain unchanged.

It doesn't explicitly mention weather stream can be NULL or not in case
of 0 size/nmemb - but regardless, is there any actual reason for not
returning early?

The following should be OK as far as I see:

-	if (!size) nmemb = 0;
+	if (!size || !nmemb) return 0;

or `if (!len) return 0;` could also work if multiplication overflow is
not a concern.

- NRK

Powered by blists - more mailing lists

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.