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Re: [PATCH] xfs: validate quota log items during log recovery

To: Eric Sandeen <sandeen@xxxxxxxxxxx>
Subject: Re: [PATCH] xfs: validate quota log items during log recovery
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Wed, 27 May 2009 05:17:34 -0400
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>, xfs@xxxxxxxxxxx
In-reply-to: <4A1C13DC.5000605@xxxxxxxxxxx>
References: <20090303175427.GA20582@xxxxxxxxxxxxx> <4A1C13DC.5000605@xxxxxxxxxxx>
User-agent: Mutt/1.5.18 (2008-05-17)
On Tue, May 26, 2009 at 11:07:56AM -0500, Eric Sandeen wrote:
> Christoph Hellwig wrote:
> > Arkadiusz has been seeing really strange crashes in xfs_qm_dqcheck that
> > I can only explain by a log item beeing too smal to actually fit the
>                                  ^^being too small^^

Thanks, corrected.

> > +                   if (item->ri_buf[i].i_addr == NULL ||
> > +                       item->ri_buf[i].i_len < sizeof(xfs_dqblk_t)) {
> > +                           cmn_err(CE_ALERT,
> > +   "XFS: dquot too small (%d) in xlog_recover_do_reg_buffer.",
> > +                                           item->ri_buf[i].i_len);
> 
> Shouldn't this differentiate between i_addr == NULL and i_len too small,
> though?  While we're at it anyway...
> 
> Maybe:

I've split both into individual checks and used __func__ to print
the function instead of hardconding it.

> >                     error = xfs_qm_dqcheck((xfs_disk_dquot_t *)
> >                                            item->ri_buf[i].i_addr,
> >                                            -1, 0, XFS_QMOPT_DOWARN,
> >                                            "dquot_buf_recover");
> > +                   if (error)
> > +                           goto next;
> 
> I guess we can't do much else, but what happens in the end, when we skip
> a buffer...

Yeah, same action a a xfs_qm_dqcheck failure.  Error handling here
probably wants to be revisited, but that should be a separate patch.


Updated patch below:


Subject: xfs: validate quota log items during log recovery
From: Christoph Hellwig <hch@xxxxxx>

Arkadiusz has seen really strange crashes in xfs_qm_dqcheck that
I can only explain by a log item being too smal to actually fit the
xfs_dqblk_t we're dereferencing all over xfs_qm_dqcheck.  So add
graceful checks for NULL or too small quota items to the log recovery
code.


Signed-off-by: Christoph Hellwig <hch@xxxxxx>

Index: xfs/fs/xfs/xfs_log_recover.c
===================================================================
--- xfs.orig/fs/xfs/xfs_log_recover.c   2009-05-27 10:40:03.752821404 +0200
+++ xfs/fs/xfs/xfs_log_recover.c        2009-05-27 10:43:23.740939498 +0200
@@ -1975,16 +1975,30 @@ xlog_recover_do_reg_buffer(
                error = 0;
                if (buf_f->blf_flags &
                   (XFS_BLI_UDQUOT_BUF|XFS_BLI_PDQUOT_BUF|XFS_BLI_GDQUOT_BUF)) {
+                       if (item->ri_buf[i].i_addr == NULL) {
+                               cmn_err(CE_ALERT,
+                                       "XFS: NULL dquot in %s.", __func__);
+                               goto next;
+                       }
+                       if (item->ri_buf[i].i_len < sizeof(xfs_dqblk_t)) {
+                               cmn_err(CE_ALERT,
+                                       "XFS: dquot too small (%d) in %s.",
+                                       item->ri_buf[i].i_len, __func__);
+                               goto next;
+                       }
                        error = xfs_qm_dqcheck((xfs_disk_dquot_t *)
                                               item->ri_buf[i].i_addr,
                                               -1, 0, XFS_QMOPT_DOWARN,
                                               "dquot_buf_recover");
+                       if (error)
+                               goto next;
                }
-               if (!error)
-                       memcpy(xfs_buf_offset(bp,
-                               (uint)bit << XFS_BLI_SHIFT),    /* dest */
-                               item->ri_buf[i].i_addr,         /* source */
-                               nbits<<XFS_BLI_SHIFT);          /* length */
+
+               memcpy(xfs_buf_offset(bp,
+                       (uint)bit << XFS_BLI_SHIFT),    /* dest */
+                       item->ri_buf[i].i_addr,         /* source */
+                       nbits<<XFS_BLI_SHIFT);          /* length */
+ next:
                i++;
                bit += nbits;
        }
@@ -2615,7 +2629,19 @@ xlog_recover_do_dquot_trans(
                return (0);
 
        recddq = (xfs_disk_dquot_t *)item->ri_buf[1].i_addr;
-       ASSERT(recddq);
+
+       if (item->ri_buf[1].i_addr == NULL) {
+               cmn_err(CE_ALERT,
+                       "XFS: NULL dquot in %s.", __func__);
+               return XFS_ERROR(EIO);
+       }
+       if (item->ri_buf[1].i_len < sizeof(xfs_dqblk_t)) {
+               cmn_err(CE_ALERT,
+                       "XFS: dquot too small (%d) in %s.",
+                       item->ri_buf[1].i_len, __func__);
+               return XFS_ERROR(EIO);
+       }
+
        /*
         * This type of quotas was turned off, so ignore this record.
         */

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