[Toybox] getline() length

[Rob Landley]

On 11/08/14 07:50, Rob wrote:
> On 8 Nov 2014 07:01, "Rob Landley" <rob at landley.net
> <mailto:rob at landley.net>> wrote:
>>
>> getline() returns an arbitrarily long line. In theory _megabytes_
>> long, which it mallocs. Could this be a denial of service attack?
...
> I don't know if this is an issue. If a user can run "grep blah
> /dev/zero" then they have shell access anyway, what's to stop them
> compiling a C program that allocates memory in a loop?

In theory a script could run grep on input from an http cgi or similar,
so the input is user controlled. It's the sort of thing that _seems_
safe... but isn't.

Again, I don't know what the correct response is. Since this is
something posix-2008 picked up from the gnu/dammit guys, it is of course
badly specified. (The FSF is a political organization with only a
vestigial software engineering effort attached, neither programming nor
documentation are anywhere near their core competency.) Specifically,
the man page's "ERRORS" section doesn't even mention -ENOMEM (let alone
-EPIPE or -EIO)... In an out of memory situation or with an input error
could it return a _short_ line? Discard partially read input if an error
occurred partway into a line? Wazzit do?

I _suppose_ on a certain level this is really libc's problem. Or at
least as much libc's problem as the user's. But "juristictional
arbitrage" does not solve problems.

Rob

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