[lxc-devel] [PATCH lxcfs 4/5] cgfs: fix dorealloc's batch allocation

[Mathias Gibbens]

  This patch also seems to fix a segfault I encountered today after
upgrading to lxcfs-0.15. My host is Debian jessie 64bit running
unprivileged jessie containers with systemd as their init. lxcfs-0.13
works, lxcfs-0.15 segfaults, and lxcfs-git at 1204f57 works again.

  In the short time since lxcfs-0.15 is out, can anyone else confirm
this?

Mathias

On Fri, 2016-01-08 at 20:10 +0000, Serge Hallyn wrote:
> > From 24e98d74ca279ed2dc8e5a025add5a00737ba952 Mon Sep 17 00:00:00
> 2001
> > From: Wolfgang Bumiller <w.bumiller at proxmox.com>
> > Date: Fri, 8 Jan 2016 11:09:57 +0100
> > Subject: [PATCH lxcfs] cgfs: make dorealloc allocate the first
> batch, too
> > 
> > With a short first line the case can be
> >  *mem = NULL
> >  oldlen = 0
> >  newlen = 5 (anything < 50)
> > making newbatches == oldbatches == 1 causing the
> >  (newbatches <= oldbatches)
> > condition to be true.
> > 
> > Let realloc() handle *mem==NULL and use
> > (!*mem || newbatches > oldbatches) as the only condition.
> > 
> > Signed-off-by: Wolfgang Bumiller <w.bumiller at proxmox.com>
> 
> Acked-by: Serge E. Hallyn <serge.hallyn at ubuntu.com>
> 
> Looks good to me, thanks.
> 
> > ---
> >  cgfs.c  | 9 +--------
> >  lxcfs.c | 2 +-
> >  2 files changed, 2 insertions(+), 9 deletions(-)
> > 
> > diff --git a/cgfs.c b/cgfs.c
> > index 1f31ed1..e6330e3 100644
> > --- a/cgfs.c
> > +++ b/cgfs.c
> > @@ -77,14 +77,7 @@ static void dorealloc(char **mem, size_t oldlen,
> size_t
> > newlen)
> >       int newbatches = (newlen / BATCH_SIZE) + 1;
> >       int oldbatches = (oldlen / BATCH_SIZE) + 1;
> >  
> > -     if (newbatches <= oldbatches)
> > -             return;
> > -
> > -     if (!*mem) {
> > -             do {
> > -                     *mem = malloc(newbatches * BATCH_SIZE);
> > -             } while (!*mem);
> > -     } else {
> > +     if (!*mem || newbatches > oldbatches) {
> >               char *tmp;
> >               do {
> >                       tmp = realloc(*mem, newbatches * BATCH_SIZE);
> > -- 
> > 2.1.4
> > 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 819 bytes
Desc: This is a digitally signed message part
URL: <http://lists.linuxcontainers.org/pipermail/lxc-devel/attachments/20160108/86e7cd9e/attachment.sig>