Dominique wrote:
> Bram Moolenaar <b...@moolenaar.net> wrote:
>
> > Patch 8.1.1653
> > Problem: Ubsan warns for possibly passing NULL pointer.
> > Solution: Skip code when length is zero. (Dominique Pelle, closes #4631)
> > Files: src/channel.c
> >
> >
> > *** ../vim-8.1.1652/src/channel.c 2019-06-28 22:06:41.110072146 +0200
> > --- src/channel.c 2019-07-08 22:01:10.759502396 +0200
> > ***************
> > *** 3990,3996 ****
> > writeq_T *last = wq->wq_prev;
> >
> > /* append to the last entry */
> > ! if (ga_grow(&last->wq_ga, len) == OK)
> > {
> > mch_memmove((char *)last->wq_ga.ga_data
> > +
> > last->wq_ga.ga_len,
> > --- 3990,3996 ----
> > writeq_T *last = wq->wq_prev;
> >
> > /* append to the last entry */
> > ! if (len > 0 && ga_grow(&last->wq_ga, len) == OK)
> > {
> > mch_memmove((char *)last->wq_ga.ga_data
> > +
> > last->wq_ga.ga_len,
> > ***************
> > *** 4012,4018 ****
> > wq->wq_prev->wq_next = last;
> > wq->wq_prev = last;
> > ga_init2(&last->wq_ga, 1, 1000);
> > ! if (ga_grow(&last->wq_ga, len) == OK)
> > {
> > mch_memmove(last->wq_ga.ga_data, buf, len);
> > last->wq_ga.ga_len = len;
> > --- 4012,4018 ----
> > wq->wq_prev->wq_next = last;
> > wq->wq_prev = last;
> > ga_init2(&last->wq_ga, 1, 1000);
> > ! if (len > 0 && ga_grow(&last->wq_ga, len) == OK)
> > {
> > mch_memmove(last->wq_ga.ga_data, buf, len);
> > last->wq_ga.ga_len = len;
>
> The 2nd chunk of the diff does not seem correct and
> is different from how I fixed it in my original PR.
>
> If len is 0, old code used to set last->wq_ga.ga_len to 0 but now
> that this is skipped. Only the mch_memmove(...) called should have
> been skipped.
That should be OK, because ga_init2() sets the length to zero.
But perhaps Ubsan doesn't handle this logic?
--
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A: All my autopsies have been performed on dead people.
/// Bram Moolenaar -- b...@moolenaar.net -- http://www.Moolenaar.net \\\
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