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Groups > gnu.bash.bug > #14383 > unrolled thread
| Started by | Chet Ramey <chet.ramey@case.edu> |
|---|---|
| First post | 2018-07-21 19:57 -0400 |
| Last post | 2018-07-21 19:57 -0400 |
| Articles | 1 — 1 participant |
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Re: v4.4 segfault in 'decode_prompt_string' when processing special parameter Chet Ramey <chet.ramey@case.edu> - 2018-07-21 19:57 -0400
| From | Chet Ramey <chet.ramey@case.edu> |
|---|---|
| Date | 2018-07-21 19:57 -0400 |
| Subject | Re: v4.4 segfault in 'decode_prompt_string' when processing special parameter |
| Message-ID | <mailman.4000.1532217489.1292.bug-bash@gnu.org> |
On 7/21/18 2:47 PM, Chris Schoenberg wrote:
> This only works in 4.4; earlier versions throw a 'bad substitution' error. It
> causes an infinite loop of calls between 'expand_prompt_string' and
> 'decode_prompt_string',
> where calls to 'xmalloc' exhaust the heap:
>
> $\{_@P};${_@P}
>
> I decided to report this because it is not a user-defined recursive
> function and it exhausts the heap rather than the stack.
It's user-defined recursive parameter expansion. A string that undergoes
prompt expansion performs parameter expansion, as documented. If that
parameter expansion passes the same string to prompt expansion, which
performs parameter expansion, you've got user-defined recursion.
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU chet@case.edu http://tiswww.cwru.edu/~chet/
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