[PATCH 1/2] Cygwin: lockf: Fix access violation in lf_clearlock().

[Takashi Yano]

On Mon, 18 Nov 2024 16:55:14 +0100
Corinna Vinschen wrote:
> On Nov 15 22:14, Takashi Yano wrote:
> > The commit ae181b0ff122 has a bug that the pointer is referred bofore
> > NULL check in the function lf_clearlock(). This patch fixes that.
> > 
> > Addresses: https://cygwin.com/pipermail/cygwin/2024-November/256750.html
> > Fixes: ae181b0ff122 ("Cygwin: lockf: Make lockf() return ENOLCK when too many locks")
> > Reported-by: Sebastian Feld <sebastian.n.feld@gmail.com>
> > Reviewed-by:
> > Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
> > ---
> >  winsup/cygwin/flock.cc | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/winsup/cygwin/flock.cc b/winsup/cygwin/flock.cc
> > index 3821bddd6..794e66bd7 100644
> > --- a/winsup/cygwin/flock.cc
> > +++ b/winsup/cygwin/flock.cc
> > @@ -1524,6 +1524,10 @@ lf_clearlock (lockf_t *unlock, lockf_t **clean, HANDLE fhdl)
> >    lockf_t *lf = *head;
> >    lockf_t *overlap, **prev;
> >    int ovcase;
> > +
> > +  if (lf == NOLOCKF)
> > +    return 0;
> > +
> >    inode_t *node = lf->lf_inode;
> >    tmp_pathbuf tp;
> >    node->i_all_lf = (lockf_t *) tp.w_get ();
> > @@ -1531,8 +1535,6 @@ lf_clearlock (lockf_t *unlock, lockf_t **clean, HANDLE fhdl)
> >    uint32_t lock_cnt = node->get_lock_count ();
> >    bool first_loop = true;
> >  
> > -  if (lf == NOLOCKF)
> > -    return 0;
> >    prev = head;
> >    while ((ovcase = lf_findoverlap (lf, unlock, SELF, &prev, &overlap)))
> >      {
> > -- 
> > 2.45.1
> 
> LGTM, please push.

Thanks for reviewing this patch. Could you please review
 [PATCH v2] Cygwin: flock: Fix overlap handling in lf_setlock() and lf_clearlock()
as well?

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>