This is the mail archive of the mailing list for the GCC project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: RFA: libiberty: Add a limit on demangling qualifiers (PR 87241)

On Wed, Dec 12, 2018 at 6:29 AM Nick Clifton <> wrote:
>   Sorry to bother you, but I have another libiberty demangler resource
>   exhaustion prevention patch to present.  This one is for:
>   Jonathan Wakely reported that __cxa_demanlge() was returning a -2
>   result, but I did not see this.  Instead I found that
>   consume_count_with_underscores() is returning a very large number
>   (because a very large value is encoded in the mangled string) and this
>   is resulting in many calls to remember_Ktype() which eventually
>   exhaust the amount of memory available.
>   The attached patch is a simplistic approach to solving this problem by
>   adding a hard upper limit on the number of qualifiers that will be
>   allowed by the demangler.  I am not sure if this is the best approach
>   to solving the problem, but it is a simple one, and I would think one
>   that would not prevent the demangling of any real mangled names.  The
>   limit does not have to be DEMANGLE_RECURSE_LIMIT of course.  I just
>   chose that value because it was convenient and of a size that I
>   thought was appropriate.
>   I also did run the libiberty testsuite this time, with no failures
>   reported. :-)
>   OK to apply ?
> Cheers
>   Nick
> libiberty/ChangeLog
> 2018-12-12  Nick Clifton  <>
>         * cplus-dem.c (demangle_qualified): Add an upper limit on the
>         number of qualifiers supported, based upon the value of

This issue also will be resolved by disabling or removing the old
demangling code, which I haven't seen anyone argue against.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]