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Handle vdev_lookup_top() failure in dva_get_dsize_sync()

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The dva_get_dsize_sync() function incorrectly assumes that the call
to vdev_lookup_top() cannot fail.  However, the NULL dereference at
clearly shows that under certain circumstances it is possible.  Note
that offset 0x570 (1376) maps as expected to vd->vdev_deflate_ratio.

  BUG: unable to handle kernel NULL pointer dereference at 00000570

  crash> struct -o vdev
  struct vdev {
       [0] uint64_t vdev_id;
       ... ...
    [1376] uint64_t vdev_deflate_ratio;

Given that this can happen this patch add the required error handling.
In the case where vdev_lookup_top() fails assume that no deflation
will occur for the DVA and use the asize.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Alexey Zhuravlev <alexey.zhuravlev@intel.com>
Closes #1707
Closes #1987
Closes #1891

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
This commit is contained in:
Brian Behlendorf 2014-05-05 11:28:12 -07:00
parent 962d524212
commit 2c33b91275
1 changed files with 3 additions and 1 deletions
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4
module/zfs/spa_misc.c
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@ -1552,7 +1552,9 @@ dva_get_dsize_sync(spa_t *spa, const dva_t *dva)
if (asize != 0 && spa->spa_deflate) { if (asize != 0 && spa->spa_deflate) {
vdev_t *vd = vdev_lookup_top(spa, DVA_GET_VDEV(dva)); vdev_t *vd = vdev_lookup_top(spa, DVA_GET_VDEV(dva));
dsize = (asize >> SPA_MINBLOCKSHIFT) * vd->vdev_deflate_ratio; if (vd != NULL)
dsize = (asize >> SPA_MINBLOCKSHIFT) *
vd->vdev_deflate_ratio;
} }
return (dsize); return (dsize);