Hey Jan,
On Wed, Jul 10, 2013 at 06:26:02PM +0200, Jan Kara wrote:
> On Wed 10-07-13 10:55:38, Ben Myers wrote:
> > Hey Chandra,
> >
> > On Thu, Jun 27, 2013 at 05:25:13PM -0500, Chandra Seetharaman wrote:
> > > Added appropriate pads and code for backward compatibility.
> > >
> > > Copied over the old version as it is different from the newer padded
> > > version.
> > >
> > > New callers of the system call have to set the version of the data
> > > structure being passed, and kernel will fill as much data as requested.
> > >
> > > Signed-off-by: Chandra Seetharaman <sekharan@xxxxxxxxxx>
> >
> > I think we also need to
> >
> > Cc: Jan Kara <jack@xxxxxxx>
> Thanks for CC.
>
> > > diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c
> > > index c7c840e..ca0dccd 100644
> > > --- a/fs/gfs2/quota.c
> > > +++ b/fs/gfs2/quota.c
> > > @@ -1443,9 +1443,6 @@ static int gfs2_quota_get_xstate(struct super_block *sb,
> > > {
> > > struct gfs2_sbd *sdp = sb->s_fs_info;
> > >
> > > - memset(fqs, 0, sizeof(struct fs_quota_stat));
> > > - fqs->qs_version = FS_QSTAT_VERSION;
> > > -
> > > switch (sdp->sd_args.ar_quota) {
> > > case GFS2_QUOTA_ON:
> > > fqs->qs_flags |= (FS_QUOTA_UDQ_ENFD | FS_QUOTA_GDQ_ENFD);
> > > diff --git a/fs/quota/quota.c b/fs/quota/quota.c
> > > index c7314f1..ae6526e 100644
> > > --- a/fs/quota/quota.c
> > > +++ b/fs/quota/quota.c
> > > @@ -207,12 +207,57 @@ static int quota_setxstate(struct super_block *sb, int cmd, void __user *addr)
> > > static int quota_getxstate(struct super_block *sb, void __user *addr)
> > > {
> > > struct fs_quota_stat fqs;
> > > - int ret;
> > > + struct fs_quota_stat_v1 fqs_v1;
> > > + int ret, size;
> > > + void *fqsp;
> > >
> > > if (!sb->s_qcop->get_xstate)
> > > return -ENOSYS;
> > > +
> > > + memset(&fqs, 0, sizeof(struct fs_quota_stat));
> > > + if (copy_from_user(&fqs, addr, 1)) /* just get the version */
> > > + return -EFAULT;
> > > +
> > > + switch (fqs.qs_version) {
> > > + case FS_QSTAT_VERSION_2:
> > > + size = FS_QSTAT_V2_SIZE;
> > > + break;
> > > + default:
> > > + fqs.qs_version = FS_QSTAT_VERSION;
> > > + /* fallthrough */
> > > + case FS_QSTAT_VERSION:
> > > + size = FS_QSTAT_V1_SIZE;
> > > + break;
> > > + }
> Guys, you cannot really do this. If anyone is using getxstate() with
> uninitialized buffer (which is fine so far), you cannot suddently start to
> rely on the contents of qs_version field. That's ABI (and even API)
> breakage.
Looks like you are correct to me. Seems that qs_version number was never
checked until this patch.
> Unless I'm missing something, the only clean way is to use new quotactl
> value for the interface with version field used for input as well.
If I understand... it would be something like this?
#define Q_XGETQSTATV XQM_CMD(8)
Or Q_XGETQSTAT2?
Thanks,
Ben
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