s390/sclp: Prevent release of buffer in I/O

When a task waiting for completion of a Store Data operation is
interrupted, an attempt is made to halt this operation. If this attempt
fails due to a hardware or firmware problem, there is a chance that the
SCLP facility might store data into buffers referenced by the original
operation at a later time.

Handle this situation by not releasing the referenced data buffers if
the halt attempt fails. For current use cases, this might result in a
leak of few pages of memory in case of a rare hardware/firmware
malfunction.

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

diff --git a/drivers/s390/char/sclp_sd.c b/drivers/s390/char/sclp_sd.c
index 5aeb7e094a1cb935dc71ee2e4f7f380f70441a3c..322700b96207da03aea5f1a15df2e043c8e4a26a 100644 (file)
--- a/drivers/s390/char/sclp_sd.c
+++ b/drivers/s390/char/sclp_sd.c
@@ -324,8 +324,14 @@ static int sclp_sd_store_data(struct sclp_sd_data *result, u8 di)
                          &esize);
        if (rc) {
                /* Cancel running request if interrupted */
-               if (rc == -ERESTARTSYS)
-                       sclp_sd_sync(page, SD_EQ_HALT, di, 0, 0, NULL, NULL);
+               if (rc == -ERESTARTSYS) {
+                       if (sclp_sd_sync(page, SD_EQ_HALT, di, 0, 0, NULL, NULL)) {
+                               pr_warn("Could not stop Store Data request - leaking at least %zu bytes\n",
+                                       (size_t)dsize * PAGE_SIZE);
+                               data = NULL;
+                               asce = 0;
+                       }
+               }
                vfree(data);
                goto out;
        }