Commit f9773768 authored Jun 21, 2016 by Sebastian Ott Committed by Martin Schwidefsky Jul 15, 2016

s390/chsc: sanitize fmt check for chp_desc determination



When fetching channel path descriptors we've only evaluated the rfmt
parameter which could lead us to trigger the chsc even though the
machine doesn't support the specific format or to not trigger the
chsc and report a failure to userspace even though the machine would've
supported it.

Improve these checks and change the parameters of the in-kernel
user to be less confusing.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

parent 0b601373

drivers/s390/cio/chsc.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -907,7 +907,8 @@ int chsc_determine_channel_path_desc(struct chp_id chpid, int fmt, int rfmt,
		struct chsc_scpd *scpd_area;
		int ccode, ret;

		if ((rfmt == 1) && !css_general_characteristics.fcs)
		if ((rfmt == 1 \|\| rfmt == 0) && c == 1 &&
		!css_general_characteristics.fcs)
		return -EINVAL;
		if ((rfmt == 2) && !css_general_characteristics.cib)
		return -EINVAL;
		@@ -966,7 +967,7 @@ int chsc_determine_fmt1_channel_path_desc(struct chp_id chpid,

		spin_lock_irqsave(&chsc_page_lock, flags);
		scpd_area = chsc_page;
		ret = chsc_determine_channel_path_desc(chpid, 0, 0, 1, 0, scpd_area);
		ret = chsc_determine_channel_path_desc(chpid, 0, 1, 1, 0, scpd_area);
		if (ret)
		goto out;
		chsc_resp = (void *)&scpd_area->response;