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From: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
To: "Karstens, Nate" <Nate.Karstens@garmin.com>,
	Matthew Wilcox <willy@infradead.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	Jeff Layton <jlayton@kernel.org>,
	"J. Bruce Fields" <bfields@fieldses.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Richard Henderson <rth@twiddle.net>,
	Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
	Matt Turner <mattst88@gmail.com>,
	"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
	Helge Deller <deller@gmx.de>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
	"linux-alpha@vger.kernel.org" <linux-alpha@vger.kernel.org>,
	"linux-parisc@vger.kernel.org" <linux-parisc@vger.kernel.org>,
	"sparclinux@vger.kernel.org" <sparclinux@vger.kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	David Laight <David.Laight@aculab.com>,
	Changli Gao <xiaosuo@gmail.com>
Subject: Re: [PATCH 1/4] fs: Implement close-on-fork
Date: Wed, 22 Apr 2020 16:31:34 +0000
Message-ID: <97f05204-a27c-7cc8-429a-edcf6eebaa11@petrovitsch.priv.at> (raw)
In-Reply-To: <6ed7bd08892b4311b70636658321904f@garmin.com>


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On 22/04/2020 16:02, Karstens, Nate wrote:
>> It's not safe to call system() from a threaded app.  That's all.  It's right there in the DESCRIPTION:
> 
> That is true, but that description is missing from both the Linux man page and the glibc documentation (https://www.gnu.org/software/libc/manual/html_mono/libc.html#Running-a-Command). It seems like a minor point that won't be noticed until it causes a problem, and problems are rare enough they might go unnoticed for a while. We have removed system() from our application, but we're also concerned that libraries we integrate will use system() without our knowledge.

Reimplementing system() is trivial.
LD_LIBRARY_PRELOAD should take care of all system(3) calls.

I wonder it it has some value to add runtime checking for
"multi-threaded" to such lib functions and error out if
yes.

Apart from that, system() is a PITA even on
single/non-threaded apps.

MfG,
	Bernd
-- 
There is no cloud, just other people computers.
-- https://static.fsf.org/nosvn/stickers/thereisnocloud.svg

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  reply index

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-20  7:15 Nate Karstens
2020-04-20  7:15 ` [PATCH 1/4] fs: " Nate Karstens
2020-04-20 10:25   ` Eric Dumazet
2020-04-22  3:38     ` Changli Gao
2020-04-22  3:41       ` Changli Gao
2020-04-22  8:35     ` David Laight
2020-05-01 14:45     ` Karstens, Nate
2020-05-01 15:23       ` Matthew Wilcox
2020-05-03 13:52       ` David Laight
2020-04-22 15:36   ` Karstens, Nate
2020-04-22 15:43     ` Matthew Wilcox
2020-04-22 16:02       ` Karstens, Nate
2020-04-22 16:31         ` Bernd Petrovitsch [this message]
2020-04-22 16:55           ` David Laight
2020-04-23 12:34             ` Bernd Petrovitsch
2020-04-20  7:15 ` [PATCH 2/4] fs: Add O_CLOFORK flag for open(2) and dup3(2) Nate Karstens
2020-04-20  7:15 ` [PATCH 3/4] fs: Add F_DUPFD_CLOFORK to fcntl(2) Nate Karstens
2020-04-20  7:15 ` [PATCH 4/4] net: Add SOCK_CLOFORK Nate Karstens
2020-04-22 14:32 ` Implement close-on-fork James Bottomley
2020-04-22 15:01 ` Al Viro
2020-04-22 15:18   ` Matthew Wilcox
2020-04-22 15:34     ` James Bottomley
2020-04-22 16:00     ` Al Viro
2020-04-22 16:13       ` Al Viro
2020-05-04 13:46       ` Karstens, Nate

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