Author: cperciva
Date: Tue Dec 13 06:54:13 2016
New Revision: 310013
URL: https://svnweb.freebsd.org/changeset/base/310013
Log:
Check that blkfront devices have a non-zero number of sectors and a
non-zero sector size. Such a device would be a virtual disk of zero
bytes; clearly not useful, and not something we should try to attach.
As a fortuitous side effect, checking that these values are non-zero
here results in them not *becoming* zero later on the function. This
odd behaviour began with r309124 (clang 3.9.0) but is challenging to
debug; making any changes to this function whatsoever seems to affect
the llvm optimizer behaviour enough to make the unexpected zeroing of
the sector_size variable cease.
PR: 215209
Security: The potential for variables to unexpectedly become zero
has worrying consequences for security in general, but
not so much in this particular context.
Modified:
head/sys/dev/xen/blkfront/blkfront.c
Modified: head/sys/dev/xen/blkfront/blkfront.c
==============================================================================
--- head/sys/dev/xen/blkfront/blkfront.c Tue Dec 13 05:09:49 2016
(r310012)
+++ head/sys/dev/xen/blkfront/blkfront.c Tue Dec 13 06:54:13 2016
(r310013)
@@ -1245,6 +1245,14 @@ xbd_connect(struct xbd_softc *sc)
xenbus_get_otherend_path(dev));
return;
}
+ if ((sectors == 0) || (sector_size == 0)) {
+ xenbus_dev_fatal(dev, 0,
+ "invalid parameters from %s:"
+ " sectors = %lu, sector_size = %lu",
+ xenbus_get_otherend_path(dev),
+ sectors, sector_size);
+ return;
+ }
err = xs_gather(XST_NIL, xenbus_get_otherend_path(dev),
"physical-sector-size", "%lu", &phys_sector_size,
NULL);
_______________________________________________
svn-src-head@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/svn-src-head
To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
