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Message-ID: <20250710215711.GZ1827@brightrain.aerifal.cx>
Date: Thu, 10 Jul 2025 17:57:11 -0400
From: Rich Felker <dalias@...c.org>
To: Markus Wichmann <nullplan@....net>
Cc: musl@...ts.openwall.com,
Luca Kellermann <mailto.luca.kellermann@...il.com>
Subject: Re: [PATCH 3/4] scandir: fix leaks caused by cancellation
On Thu, Jul 10, 2025 at 09:19:24PM +0200, Markus Wichmann wrote:
> Am Thu, Jul 10, 2025 at 08:51:30PM +0200 schrieb Luca Kellermann:
> > opendir(), sel(), closedir(), or cmp() might act upon a cancellation
> > request. because scandir() did not install a cancellation cleanup
> > handler, this could lead to memory and file descriptor leaks.
>
> scandir() is on the "may be cancel-point" list in POSIX-2024, so it
> would also be acceptable to just disable cancellation for the duration
> of the function (since it's not on the "shall be cancel-point" list).
Yes, generally we do not support cancellation for the "may be a
cancellation point" functions except in some trivial cases. Here it's
complicated by the fact that we're calling back to application code,
and scandir is underspecified in that it doesn't actually specify what
happens if the sel or compar function does not return in the normative
text. However, the APPLICATION USAGE section mentions this possibility
and advises applications not to do it, but doesn't seem to forbid it.
Rich
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