Commit bf365071 authored by Peter Oberparleiter's avatar Peter Oberparleiter Committed by Alexander Gordeev
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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: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarPeter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: default avatarAlexander Gordeev <agordeev@linux.ibm.com>
parent ecec74bb

drivers/s390/char/sclp_sd.c

+8 −2
Original line number Diff line number Diff line
@@ -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;

	}