xfs: validate quota log items during log recovery

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@lst.de>
Reviewed-by: Eric Sandeen <sandeen@sandeen.net>

1 files changed, 32 insertions, 6 deletions

diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 7ba450116d4f..47da2fb45377 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -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.
          */