[XFS] Fix use-after-free during log unmount.
Don't reference the log buffer after running the callbacks as the callback
can trigger the log buffers to be freed during unmount.
SGI-PV: 964545
SGI-Modid: xfs-linux-melb:xfs-kern:28567a
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tim Shimmin <tes@sgi.com>
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 635f99e..5bb9020 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -967,14 +967,16 @@
} else if (iclog->ic_state & XLOG_STATE_IOERROR) {
aborted = XFS_LI_ABORTED;
}
+
+ /* log I/O is always issued ASYNC */
+ ASSERT(XFS_BUF_ISASYNC(bp));
xlog_state_done_syncing(iclog, aborted);
- if (!(XFS_BUF_ISASYNC(bp))) {
- /*
- * Corresponding psema() will be done in bwrite(). If we don't
- * vsema() here, panic.
- */
- XFS_BUF_V_IODONESEMA(bp);
- }
+ /*
+ * do not reference the buffer (bp) here as we could race
+ * with it being freed after writing the unmount record to the
+ * log.
+ */
+
} /* xlog_iodone */
/*