On Sun, 3 May 2020, Noel Duffy via fpc-pascal wrote:
On Sun, 3 May 2020 09:57:46 +0200 (CEST) Michael Van Canneyt
<mich...@freepascal.org> wrote:
On Sun, 3 May 2020, Noel Duffy via fpc-pascal wrote:
The problem is that the StrToHostAddr6 function doesn't set its return
value until the end of the function. If a parse error occurs
mid-function, it zeroes the record in which it's writing the result but
exits without setting the function return value. What gets returned
depends on what's on the stack.
I could have sworn that fpc would detect a function exiting without
setting a return value, but clearly 3.0.4 doesn't.
It checks if the result is assigned. This is done;
But it does not check this for every exit, as far as I know it never has.
That seems like it would be a valuable feature to have. I am not certain
what's contained in an uninitialized variable that gets returned from a
function but I'd guess there's a risk of information leakage.
That's why the compiler warns about use of uninitialized variables.
But there will always be corner cases the compiler does not catch.
For the part before the first colon, it has discarded all but the last
two bytes, A2 and F1. But it should not have accepted this string at
all. There can be only four characters between the colons.
If you send a patch for this, I'll apply it.
Sure I can take a stab at this. Do you normally get people to open a bug
against which to post the patch? I'm not at all familiar with
contributing to fpc, I'm afraid, so please bear with me! Also, if
there's information on unit testing for library functions and
procedures, that would be very helpful.
Yes, please open a bug report. If you attach a small console test program that
demonstrates the bug (and subsequently the fix) then I will make sure it
ends up in the correct place. If you make sure it exits with exit code 0 if all
is
well, and a nonzero exit code if there is an error, that will save me some
work. If you post the URL for the bug here, I will look at it at once.
Thanks for pointing it out!
Michael.
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