[ast-developers] Fwd: Executing shell code on the signal stack, or why is this is a bad idea

[Lionel Cons]

Followup. So Chet Ramey <chet.ramey at case.edu> (bash author) is (like
Roland Mainz suggested) now executing trap commands outside signal
handlers.

One measured advantage is that the shell no longer has to disable,
defer and enable signals, cutting down the syscall overhead for signal
handling considerably and can no longer fall victim to buggy signal
implementations.

Lionel

---------- Forwarded message ----------
From: Chet Ramey <chet.ramey at case.edu>
Date: 7 June 2013 22:50
Subject: Re: Executing shell code on the signal stack, or why is this
is a bad idea
To: Lionel Cons <lionelcons1972 at googlemail.com>
Cc: bug-bash at gnu.org, chet.ramey at case.edu

Forwarding an interesting posting from Roland Mainz who did an
investigation why signal trap processing in ksh93, bash and dash is
currently not reliable.

As I said in a previous message, I have done considerable work between
bash-4.2 and bash-4.3 to move signal processing out of signal handlers.
This includes running trap commands.

Read the thread beginning at

http://lists.gnu.org/archive/html/bug-bash/2012-11/msg00003.html

for a discussion that kicked off some of the work.

Chet

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU chet at case.edu http://cnswww.cns.cwru.edu/~chet/