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From: Jakub Jelinek <jakub@redhat.com>
To: Nick Clifton <nickc@redhat.com>
Cc: Michael Matz <matz@suse.de>, Ian Lance Taylor <iant@google.com>,
	       "H.J. Lu" <hjl.tools@gmail.com>,
	Pedro Alves <palves@redhat.com>,
	       Richard Guenther <richard.guenther@gmail.com>,
	sgayou@redhat.com,        Tom Tromey <tom@tromey.com>,
	GCC Patches <gcc-patches@gcc.gnu.org>,
	       Binutils <binutils@sourceware.org>,
	Jason Merrill <jason@redhat.com>
Subject: Re: [PATCH] Set DEMANGLE_RECURSION_LIMIT to 1536
Date: Mon, 10 Dec 2018 15:18:00 -0000	[thread overview]
Message-ID: <20181210151846.GB12380@tucnak> (raw)
In-Reply-To: <9e739bbc-38a2-c3b1-3b2b-f8de4b755d47@redhat.com>

On Mon, Dec 10, 2018 at 03:12:53PM +0000, Nick Clifton wrote:
> Hi Michael,
> 
> > I think this points toward the limit being _much_ too low.
> 
> Fair enough - several other people have said this as well.  So
> I have proposed an alternative patch instead.  My current suggestion
> is to raise the limit to 2048, which allows the libiberty patch to 
> pass.  But do you have a feel for how much is a realistic limit ?

For recursion limit I think that is fine.
For just stack size limit, I think it is extremely small.
I see that in the function it allocates on 64-bit 24 bytes times
num_comps using alloca, so 48 bytes per character in the mangled name,
and a pointer for each character in the mangled name.
That is 112KB per 2048 bytes long mangled name.

Dunno how much stack can we expect to be usable.

	Jakub

  reply	other threads:[~2018-12-10 15:18 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-30  8:38 RFA/RFC: Add stack recursion limit to libiberty's demangler Nick Clifton
2018-11-30  8:42 ` Jakub Jelinek
2018-11-30 10:27   ` Nick Clifton
2018-11-30 13:46     ` Michael Matz
2018-11-30 14:57       ` Ian Lance Taylor
2018-12-02  0:49         ` Cary Coutant
2018-12-03 14:53           ` Nick Clifton
2018-12-03 22:00           ` Joseph Myers
2018-11-30 13:56     ` Ian Lance Taylor
2018-11-30 14:03       ` Jakub Jelinek
2018-11-30 17:41         ` RFA/RFC: Add stack recursion limit to libiberty's demangler [v3] Nick Clifton
2018-11-30 17:49           ` Jakub Jelinek
2018-11-30 18:19           ` Pedro Alves
2018-12-03 10:28           ` Richard Biener
2018-12-03 14:45             ` Nick Clifton
2018-12-03 18:49               ` Ian Lance Taylor via gcc-patches
2018-12-04 14:00                 ` RFA/RFC: Add stack recursion limit to libiberty's demangler [v4] Nick Clifton
2018-12-04 15:02                   ` Pedro Alves
2018-12-04 16:57                     ` RFA/RFC: Add stack recursion limit to libiberty's demangler [v5] Nick Clifton
2018-12-04 17:08                       ` Pedro Alves
2018-12-06 11:12                         ` Nick Clifton
2018-12-06 18:04                           ` Ian Lance Taylor via gcc-patches
2018-12-07 16:17                             ` H.J. Lu
2018-12-07 16:25                               ` [PATCH] Set DEMANGLE_RECURSION_LIMIT to 1536 H.J. Lu
2018-12-10 14:52                                 ` Michael Matz
2018-12-10 15:10                                   ` Jakub Jelinek
2018-12-10 15:34                                     ` Jason Merrill
2018-12-11  0:33                                       ` Jeff Law
2018-12-11  6:58                                         ` Jakub Jelinek
2018-12-11 11:05                                           ` Pedro Alves
2018-12-11 14:26                                             ` Ian Lance Taylor via gcc-patches
2018-12-11 15:07                                               ` Pedro Alves
2018-12-11 10:34                                         ` Pedro Alves
2018-12-10 15:12                                   ` Nick Clifton
2018-12-10 15:18                                     ` Jakub Jelinek [this message]
2018-12-10 15:26                                       ` Nick Clifton
2018-12-10 15:35                                         ` Jakub Jelinek
2018-12-10 18:20                                           ` Ian Lance Taylor via gcc-patches
2018-12-10 18:55                                             ` Jakub Jelinek
2018-12-10 23:47                                               ` Jason Merrill
2018-12-10 15:18                                   ` David Malcolm
2018-12-10 15:31                                     ` Nick Clifton
2018-12-06 16:14                       ` RFA/RFC: Add stack recursion limit to libiberty's demangler [v5] Jason Merrill
2018-12-06 21:22                         ` RFC: libiberty PATCH to disable demangling of ancient mangling schemes Jason Merrill
2018-12-07 10:27                           ` Nick Clifton
2018-12-07 10:40                             ` Jakub Jelinek
2018-12-07 16:11                               ` Pedro Alves
2018-12-07 17:49                                 ` Tom Tromey
2018-12-07 21:00                                   ` Jason Merrill
2018-12-14 22:39                                     ` Jason Merrill
2018-12-16  4:50                                       ` Simon Marchi
2018-12-07 16:28                               ` Nick Clifton
2018-12-07 11:37                           ` Richard Biener
2018-12-07 15:49                             ` Jason Merrill
2018-12-10  1:04                               ` Eric Gallager

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