[PATCH] scsi: fix use-after-free in scsi_init_io()

[Tejun Heo <tj@kernel.org>]

scsi_init_io() dereferences scsi_cmnd after putting it in the error
path leading to oops.  Fix it.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@kernel.org
---
 drivers/scsi/scsi_lib.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Index: block/drivers/scsi/scsi_lib.c
===================================================================
--- block.orig/drivers/scsi/scsi_lib.c
+++ block/drivers/scsi/scsi_lib.c
@@ -968,7 +968,9 @@ static int scsi_init_sgtable(struct requ
  */
 int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask)
 {
+	struct request *req = cmd->request;
 	int error = scsi_init_sgtable(cmd->request, &cmd->sdb, gfp_mask);
+
 	if (error)
 		goto err_exit;

@@ -1012,7 +1014,7 @@ int scsi_init_io(struct scsi_cmnd *cmd,
 err_exit:
 	scsi_release_buffers(cmd);
 	scsi_put_command(cmd);
-	cmd->request->special = NULL;
+	req->special = NULL;
 	return error;
 }
 EXPORT_SYMBOL(scsi_init_io);