xfs: avoid null *src in memcpy call in xlog_write
The gcc undefined behavior sanitizer caught this; surely
any sane memcpy implementation will no-op if size == 0,
but behavior with a *src of NULL is technically undefined
(declared nonnull), so avoid it here.
We are actually in this situation frequently via
xlog_commit_record(), because:
struct xfs_log_iovec reg = {
.i_addr = NULL,
.i_len = 0,
.i_type = XLOG_REG_TYPE_COMMIT,
};
Reported-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 0c8ef76..af08326 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -2422,11 +2422,20 @@
&partial_copy_len);
xlog_verify_dest_ptr(log, ptr);
- /* copy region */
+ /*
+ * Copy region.
+ *
+ * Unmount records just log an opheader, so can have
+ * empty payloads with no data region to copy. Hence we
+ * only copy the payload if the vector says it has data
+ * to copy.
+ */
ASSERT(copy_len >= 0);
- memcpy(ptr, reg->i_addr + copy_off, copy_len);
- xlog_write_adv_cnt(&ptr, &len, &log_offset, copy_len);
-
+ if (copy_len > 0) {
+ memcpy(ptr, reg->i_addr + copy_off, copy_len);
+ xlog_write_adv_cnt(&ptr, &len, &log_offset,
+ copy_len);
+ }
copy_len += start_rec_copy + sizeof(xlog_op_header_t);
record_cnt++;
data_cnt += contwr ? copy_len : 0;